Apparatus for transmitting torque in the power trains of motor vehicles

ABSTRACT

An apparatus for transmitting torque between the output element of an internal combustion engine and the input element of a variable-speed transmission in a motor vehicle has a first flywheel which is screwed or bolted to the output element and a second flywheel which is coaxial with and rotatable relative to the first flywheel and is connected to the input element by the clutch plate of a friction clutch. One or more dampers are provided in a lubricant-containing annular chamber of the first flywheel to oppose rotation of the flywheels relative to each other, and each damper has an annulus of arcuate coil springs acting in the circumferential direction of the flywheels. The cover of the clutch has stressing arms which extend into the chamber and engage the springs.

BACKGROUND OF THE INVENTION

The invention relates to improvements in torque transmitting apparatus,especially to apparatus which can be used to transmit torque between theengine and the variable-speed transmission of a motor vehicle.

Published German patent application No. 37 21 706 of Wolfgang Reik(published Jan. 7, 1988) discloses a torque transmitting apparatuswherein a first flywheel is connected to the rotary output element of anengine and a second flywheel is connected with the input element of avariable-speed transmission by way of a friction clutch. An antifrictionroller bearing is interposed between the two flywheels and a damper isemployed to oppose rotation of the flywheels relative to each other. Thedamper is installed in an annular chamber which is defined in part bythe first flywheel and includes energy storing elements acting in thecircumferential direction of the flywheels. The chamber is at leastpartially filled with a viscous fluid and is at least substantiallysealed from the surrounding atmosphere. The friction clutch has a coverwhich is secured to the second flywheel.

Torque transmitting apparatus employing composite flywheels of the aboveoutlined character have found wide acceptance in the automobile industrySuch apparatus are used primarily in motor vehicles with ample roombelow the hood, particularly in motor vehicles of the type wherein theengine block and the transmission extend in the direction of forwardmovement of the vehicle. Heretofore known torque transmitting apparatusof the above outlined character are less satisfactory for use in motorvehicles wherein the space beneath the hood is at a premium, especiallyin motor vehicles of the type wherein the combustion engine and thevariable-speed transmission are installed to extend transversely of thedirection of forward movement of the vehicle. On the other hand, torquetransmitting apparatus of the above outlined character exhibit a numberof important advantages so that there exists an urgent need forapparatus which embody the above-enumerated features and can be utilizedin practically all kinds of vehicles including those withengine-transmission assemblies extending in, and those withengine-transmission assemblies extending transversely of, the directionof forward movement of the vehicle.

OBJECTS OF THE INVENTION

An object of the invention is to provide a torque transmitting apparatuswhich constitutes an improvement over and a further development ofapparatus disclosed in published German patent application No. 37 21706.

Another object of the invention is to provide a torque transmittingapparatus which can be used in motor vehicles having longitudinally ortransversely extending engine-transmission assemblies without occupyingany additional space, or much additional space, beneath the hood.

A further object of the invention is to provide a torque transmittingapparatus which is constructed and assembled in such a way that it canbe installed in a motor vehicle within a short interval of time and byresorting to available tools.

An additional object of the invention is to provide the apparatus withnovel and improved means for reducing the dimensions in the axialdirection of the flywheels.

Still another object of the invention is to provide the torquetransmitting apparatus with novel and improved means for preventingoverheating of certain parts

Another object of the invention is to provide the apparatus with noveland improved means for sealing the supply of viscous fluid in thechamber for the damper or dampers between the flywheels

A further object of the invention is to provide an apparatus which isideally suited for use in motor vehicles with longitudinally extendingengine-transmission assemblies as well as in motor vehicles withtransversely extending engine-transmission assemblies.

Another object of the invention is to provide a torque transmittingapparatus wherein the flywheels occupy a minimal amount of space.

An additional object of the invention is to provide a torquetransmitting apparatus which renders it possible to achieve optimaltorque transmitting and damping rates.

Another object of the invention is to provide a simple, compact andinexpensive torque transmitting apparatus which can be used in existingtypes of motor vehicles

A further object of the invention is to provide the above outlinedapparatus with novel and improved means for securing the friction clutchto one of the flywheels.

An additional object of the invention is to provide a novel and improvedmethod of assembling the parts of the above outlined torque transmittingapparatus.

A further object of the invention is to provide a torque transmittingapparatus which is constructed and assembled in such a way that theparts which are used to secure one of the flywheels to the outputelement of the engine cannot be misplaced or lost during storage and/orduring transport to an automobile assembling plant or to a repair shop.

Another object of the invention is to provide the torque transmittingapparatus with novel and improved means for preventing overheating ofcertain sensitive parts.

An additional object of the invention is to provide an apparatus whichutilizes flywheels that can be mass-produced at a fraction of the costof heretofore known flywheels.

Another object of the invention is to provide a torque transmittingapparatus wherein various rotary parts can be properly centered prior toinstallation in a motor vehicle

A further object of the invention is to provide a motor vehicle whichembodies the above outlined torque transmitting apparatus.

An additional object of the invention is to provide a novel and improvedblank which can be subdivided into several component parts of the aboveoutlined torque transmitting apparatus.

Another object of the invention is to provide the apparatus with noveland improved means for facilitating the placing of the flywheels intoimmediate or very close proximity to each other in order to enhance thecompactness of the apparatus in the axial direction of the flywheels.

An additional object of the invention is to provide a torquetransmitting apparatus which can be manipulated by semiskilled persons.

Another object of the invention is to provide the torque transmittingapparatus with novel and improved means for deforming or stressing theenergy storing means of the damper or dampers in the liquid-containingchamber.

SUMMARY OF THE INVENTION

One feature of the present invention resides in the provision of atorque transmitting apparatus which can be used in motor vehicles. Theimproved apparatus comprises a first rotary flywheel which isconnectable with an engine of the vehicle (e.g., to the rotary outputelement--such as a crankshaft--of an internal combustion engine), asecond rotary friction wheel which is coaxial with the first flywheeland is connectable with the input shaft of a transmission in thevehicle, at least one antifriction (ball, roller, needle or like)bearing between the first and second flywheels, and at least one damperwhich is operative to oppose rotation of the first and second flywheelsrelative to each other and is disposed in an annular chamber defined atleast in part by the first flywheel. The damper includes energy storingelements (e.g., coil springs) acting in the circumferential direction ofthe flywheels and the second flywheel is connectable to the inputelement of the transmission by a friction clutch having a cover which isaffixed to the second flywheel and is provided with stressing portionsextending into the annular chamber and engaging the energy storingelements of the at least one damper.

The stressing portions can but need not be integral with the cover ofthe friction clutch.

The apparatus preferably further comprises a supply of viscous fluid(e.g., oil or grease) which at least partially fills the annularchamber, and means for at least substantially sealing the chamber fromthe atmosphere. The sealing means can comprise an O-ring or anothersuitable sealing element which can be interposed between the outer sideof the cover of the friction clutch and a component (e.g., asubstantially radially extending annular wall) which defines a portionof the annular chamber. The sealing element can be mounted directly onthe aforementioned component or wall. Alternatively, the sealing elementcan be mounted on the cover of the friction clutch.

The cover can at least partially surround the second flywheel. Suchapparatus can comprise means (e.g., integral projections of the cover)for connecting the cover to the second flywheel at the peripheralsurface of the second flywheel, i.e., the latter can be at leastsubstantially or fully confined in the cover of the friction clutch.

The stressing portions for the energy storing elements of the at leastone damper can be provided on one or more securing members which areaffixed to the cover. The stressing portions can form integral parts ofthe securing member or members. The securing member or members can beaffixed to the outer marginal portion of the cover.

A membrane can be used as a means for affixing the cover of the frictionclutch to the second flywheel. The membrane can surround the secondflywheel and can be secured to the outer marginal portion of the cover.For example, a portion of the membrane can be clamped between the outermarginal portion of the cover and the aforementioned securing member ormembers. The membrane can extend along that side of the second flywheelwhich confronts the first flywheel and faces away from the frictionclutch. To this end, a portion of the membrane preferably extendsradially of the first flywheel and along the aforementioned side of thesecond flywheel. Such side of the second flywheel can be provided withat least one ventilating channel which is overlapped by the radiallyextending portion of the membrane. The at least one channel has an inletportion and an outlet portion and one of these inlet and outlet portionsis nearer to and the other of such inlet and outlet portions is moredistant from the at least one bearing and from the axis of the secondflywheel. A portion of the membrane can serve as a means for centeringthe friction clutch relative to the second flywheel and vice versa.

The second flywheel has a substantially radially extending frictionsurface adjacent a clutch plate of the friction clutch A pressure platewhich rotates with the second flywheel is installed between the coverand the clutch plate of the friction clutch. The radially inner portionof the at least substantially sealed annular chamber can extend radiallyinwardly from the outermost toward but short of the innermost portion offriction surface on the second flywheel. The radially inner portion ofthe annular chamber preferably terminates at or short of a locationmidway between the radially innermost and outermost portions of thefriction surface.

Two relatively large portions of the first and second flywheels arepreferably located close to each other radially inwardly of the annularchamber to define a relatively narrow clearance, e.g., a clearancehaving a width of 1 to 4 mm. The clearance can extend radially outwardlyfrom the common axis of the flywheels toward the radially inner portionof the annular chamber, e.g., at least to a location not less thanhalfway between the radially innermost and outermost portions of thefriction surface on the second flywheel. The clearance is preferablyadjacent a substantially disc-shaped portion of the first flywheel, andsuch disc-shaped portion is connected or is connectable directly to therotary output element of the engine.

At least a portion of the friction surface on the second flywheel can belocated in a plane which is normal to the axes of the flywheels and isadjacent or intersects the at least one bearing. Such bearing is locatedradially inwardly of the friction surface.

The aforementioned clearance between the two flywheels can serve as aventilating path for the flow of a cooling air stream to reduce thetransfer of heat from the friction surface of the second flywheel to thefirst flywheel.

That portion of the first flywheel which is adjacent the clearance canbe provided with one or more openings which communicate with theclearance. The second flywheel can be provided with one or more openingswhich communicate with the clearance; such opening or openings can beprovided radially inwardly and/or radially outwardly of the frictionsurface on the second flywheel.

That portion of the first flywheel which is adjacent the clearance andis connectable to the output element of the engine is preferablyintegral with an axially extending annular portion and surrounds theradially outermost portion of the annular chamber. The chamber isfurther bounded by the aforementioned component or wall which isadjacent to the annular portion of the chamber and is disposed radiallyoutwardly of the friction surface on the second flywheel. The wall cansurround the cover of the friction clutch or the aforementioned securingmember or members.

The aforementioned sealing means can further comprise a seal which isdisposed in the clearance between the first and second flywheels. Suchseal can be installed to sealingly engage the first flywheel and thecover or to sealingly engage the first flywheel and the aforementionedsecuring member or members.

The means for fastening the first flywheel to the output element of theengine can be located radially inwardly of the at least one bearing. Inaccordance with a presently preferred embodiment, the fastening meanscan comprise a plurality of rotary fasteners (e.g., in the form ofscrews or bolts) which are located radially outwardly of the at leastone bearing. The fasteners have heads at that (inner) side of the firstflywheel which confronts the clearance and externally threaded shankswhich extend through the respective openings and into tapped bores ofthe output element of the engine when the improved apparatus is properlyinstalled in a motor vehicle. The second flywheel can be provided withopenings which preferably extend in parallelism with the axes of theflywheels and are positioned to permit engagement of the heads offasteners by a rotating (torque transmitting) tool, e.g., a manuallyoperated or motor driven wrench.

The flywheels define an axial passage for a component (such as theaforementioned input shaft) of the transmission. The at least onebearing surrounds the passage and the aforementioned openings or holesof the first flywheel are located radially outwardly of the passage toreceive the respective fasteners which serve to secure the firstflywheel to the engine. As mentioned above, the openings or holes of thefirst flywheel can be located radially outwardly of the at least onebearing and can be in partial or full alignment with the openings orholes of the second flywheel. This enables a torque transmitting tool toreach the heads of fasteners by extending through the openings or holesof the second flywheel.

One of the flywheels (e.g., the first flywheel) can be provided with anannular protuberance, and the at least one bearing is then mounted insuch a way that it surrounds the protuberance. The arrangement may besuch that the at least one bearing is provided with an inner race whichsurrounds the protuberance of the one flywheel, and with an outer racewhich surrounds the inner race and supports the other flywheel. Theholes or openings of the first flywheel are preferably located radiallyoutwardly of the inner and outer races of the at least one bearing. Theprotuberance can be an integral part of the one (first or second)flywheel.

The hub of the clutch plate can extend into the aforementioned axialpassage of the flywheels.

The openings or holes in the second flywheel are preferably dimensionedin such a way that they afford access to but prevent the passage of theheads of registering fasteners. This ensures that, once the apparatus isassembled, the fasteners can be loosened to be detached from the outputelement of the engine but cannot be lost because their shanks arecompelled to extend into the respective openings or holes of the firstflywheel. If the heads of the fasteners are round and the holes oropenings of the second flywheel are round, the diameters of the headsexceed the diameters of the holes or openings in the second flywheel.

The aforementioned protuberance can be made integral with the at leastone bearing. For example, the inner or the outer race of the at leastone bearing can be an integral part of the protuberance. Theprotuberance can be made integral with the first flywheel and can beintegral with the outer race of the at least one bearing.

The flywheels and the friction clutch (including the cover, the pressureplate and the clutch plate) can constitute a preassembled unit which canbe shipped to customers or stored prior or subsequent to shipment. Thepreassembled unit is ready to be affixed to the output element of anengine, and such unit preferably further comprises the at least onebearing. The means for preventing complete withdrawal of fasteners fromthe preassembled unit can comprise the second flywheel or other suitablemeans, e.g., one or more deformable parts which can yield when thefasteners are driven home to reliably connect the first flywheel to thecrankshaft of an internal combustion engine.

The clutch plate of the friction clutch is preferably centered in thepreassembled unit between the second flywheel and the pressure plate.This ensures that the axis of the clutch plate coincides with the axisof the rotary output element when the unit is properly attached to theengine.

If necessary, the clutch plate and/or the pressure plate of the frictionclutch can be provided with holes or bores which afford access to theheads of fasteners at the inner side of the aforementioned substantiallydisc-shaped portion of the first flywheel. When the clutch plate isproperly centered between the second flywheel and the pressure plate,its holes are in at least partial alignment with the holes of thepressure plate and with the openings or holes (if any) in the secondflywheel so that a tool can be caused to engage and rotate the heads offasteners in order to drive the fasteners into or to withdraw the fromthe output element. Each hole of the first flywheel can register with ahole in the clutch plate. The dimensions of holes in the diaphragmspring are such that the spring prevents the heads of fasteners frompassing through its holes. The same preferably applies for the holes inthe clutch plate.

The friction clutch preferably defines an internal space which isconfigurated and dimensioned in such a way that the heads of thefasteners can be accommodated therein while the shanks of such fastenersextend into but not beyond the openings or holes in the substantiallydisc-shaped portion of the first flywheel. This contributes toconvenience of attachment of the preassembled unit (including the twoflywheels, the friction clutch, the at least one damper and the at leastone bearing) to the output element of the engine.

One of the flywheels (particularly the first flywheel) can carry a pilotbearing for the input element of the transmission.

The friction clutch can be separably coupled to the second flywheel.

The cover of the friction clutch can include an axially extendingradially outer portion which is adjacent the annular chamber, and thechamber can extend radially of the cover and can surround the radiallyouter portion of the cover.

The aforementioned stressing portions for the energy storing elements ofthe at least one damper can be provided on the axially extendingradially outer portion of the cover; such stressing portions can bedisposed substantially radially of the axially extending radially outerportion.

The stressing portions can include or constitute discrete lugs which areaffixed to the cover. If the cover includes an axially extendingradially outer portion which has a free end at the first flywheel, thestressing portions can be provided at the exterior of the axiallyextending portion and can be spaced apart from the free end.

The energy storing elements of the at least one damper can be radiallyoutwardly adjacent the axially extending portion of the cover.

The aforementioned wall (which bounds a portion of the annular chamber)can surround portions of the energy storing elements and can be made ofthe same material as the cover of the friction clutch. The normallyflange-like carrier of friction linings forming part of the clutch platecan also be made of a material which is the same as that of the walland/or the cover. In order to reduce the cost of the improved apparatus,the cover of the friction clutch, the carrier of the clutch plate andthe wall can constitute separated sections of an originally one-pieceblank.

The connection between the cover of the friction clutch and the secondflywheel can be a permanent connection, e.g., a connection consisting ofor including one or more welded seams or spot welds.

A thermal insulator can be installed between the second flywheel and theannular chamber and/or between the second flywheel and the stressingportions for the energy storing elements of the at least one damperand/or between the cover and the second flywheel.

If the cover of the friction clutch has an axially extending portionwhich surrounds the second flywheel, the connection between the coverand the second flywheel can comprise at least one projection whichextends into a radial recess of the second flywheel. The recess can be asubstantially cruciform recess which is obtained by providing theperipheral surface of the second flywheel with at least onecircumferentially extending groove and with at least one axiallyparallel groove which intersects the circumferentially extending groove.The projection of the axially extending portion of the cover of thefriction clutch is substantially complementary to and extends into thecruciform or substantially cruciform recess which is formed at theintersection of the circumferentially extending and axially parallelgrooves. The two grooves can cross each other at an angle ofsubstantially or exactly 90°. The second flywheel can be provided with aconcave surface which bounds the axially parallel groove. The projectionof the axially extending portion of the cover can constitute an integralpart of the axially extending portion which is stamped to flow into theintersection of the circumferentially extending and axially parallelgrooves.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first flywheel connectable withthe engine of a motor vehicle, a second flywheel connectable with atransmission of the vehicle by a friction clutch having a cover which isconnected to the second flywheel, at least one damper which is operativeto oppose rotation of the flywheels relative to each other and isdisposed at least in part in an annular chamber defined at least in partby the first flywheel, a wall or another suitable component defininganother part of the chamber, a supply of viscous fluid which at leastpartially fills the chamber, and means for at least substantiallysealing the chamber from the atmosphere. The sealing means comprises asealing element which is interposed between the external surface of thecover and the aforementioned component.

A further feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheelconnectable to the engine of a motor vehicle, a second rotary flywheelwhich is coaxial with the first flywheel and is connectable to atransmission of the vehicle by a friction clutch having a cover, apressure plate on the cover, and a clutch plate between the pressureplate and a friction surface of the second flywheel, at least one damperwhich is operative to oppose rotation of the flywheels relative to eachother and is disposed in an annular chamber defined at least in part bythe first flywheel, a supply of viscous fluid which at least partiallyfills the chamber, and means for at least substantially sealing thechamber from the atmosphere. The chamber has a radially inner portionwhich extends radially inwardly from the outermost portion of thefriction surface toward but short of the radially innermost portion ofthe friction surface. It is presently preferred that the radially innerportion of the annular chamber terminate at most midway between theradially innermost and outermost portions of the friction surface.

An additional feature of the invention resides in the provision of atorque transmitting apparatus which comprises a first rotary flywheelconnectable with the engine of a motor vehicle, a second rotary flywheelwhich is connectable with the transmission of the vehicle, and at leastone damper which is operative to oppose rotation of the two flywheelsrelative to each other and is disposed in a sealed annular chamberdefined at least in part by one of the flywheels. The flywheels haveportions which define a narrow clearance and confront each otherradially inwardly of the annular chamber.

Still another feature of the invention resides in the provision of atorque transmitting apparatus which comprises a first rotary flywheelhaving a substantially radially extending disc-shaped portionconnectable with the engine of a motor vehicle, a second rotary flywheelwhich is connectable with the transmission of the vehicle by a frictionclutch, and at least one damper which is operative to oppose rotation ofthe flywheels relative to each other and is disposed in an annularchamber defined in part by an axially extending portion which is rigidwith the disc-shaped portion of the first flywheel. The chamber has aradially outermost portion which is surrounded by the axially extendingportion, and the apparatus further comprises an annular wall which isadjacent the axially extending portion and bounds a portion of theannular chamber. The second flywheel has an annular friction surfaceadjacent a clutch plate of the friction clutch, and the wall is disposedradially outwardly of the friction surface.

A further feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheelconnectable with the engine of a vehicle, a second rotary flywheel whichis connectable with a transmission of the vehicle by a friction clutchhaving a pressure plate and a clutch plate between the pressure plateand an annular friction surface of the second flywheel, at least oneantifriction bearing between the two flywheels, and at least one damperoperative to oppose rotation of the flywheels relative to each other anddisposed in an annular chamber which is at least partially filled with aviscous fluid and is defined at least in part by one of the flywheels.The at least one damper has coil springs and/or other suitable energystoring elements which are installed in a toroidal portion of thechamber, and the apparatus further comprises means for at leastsubstantially sealing the chamber from the atmosphere. The sealing meanscomprises a sealing element between a first component which is rotatablewith the first flywheel and a second component which is rotatable withthe second flywheel. The one flywheel has a surface bounding thetoroidal portion of the chamber and closely following the outlines ofadjacent portions of energy storing elements in the toroidal portion.The sealing element and the toroidal portion of the chamber are locatedradially outwardly of the second flywheel. The two flywheels includeneighboring portions which extend substantially radially inwardly fromthe toroidal portion of the chamber and define a preferably narrowclearance.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheel, a secondrotary flywheel which is connectable with the transmission of a motorvehicle by a friction clutch, at least one antifriction bearing betweenthe flywheels, and at least one damper which is operative to opposerotation of the flywheels relative to each other and is disposed in aliquid-containing annular chamber of one of the flywheels. The firstflywheel has a plurality of holes which are surrounded by the at leastone bearing, and the apparatus further comprises means for fastening thefirst flywheel to a rotary output element of the engine of the motorvehicle. The fastening means comprises discrete fasteners which extendinto the holes of the first flywheel.

An additional feature of the invention resides in the provision of atorque transmitting apparatus which comprises a first rotary flywheel, asecond rotary flywheel which is connectable with the transmission of amotor vehicle, at least one damper which is operative to oppose rotationof the flywheels relative to each other, at least one antifrictionbearing between the flywheels, and means for fastening the firstflywheel to a rotary output element of the engine of the motor vehicle.The fastening means includes fasteners which are disposed radiallyoutwardly of the at least one bearing.

Still another feature of the invention resides in the provision of atorque transmitting apparatus which comprises a first rotary flywheel, asecond rotary flywheel which is connectable with the transmission of amotor vehicle, and at least one antifriction bearing between theflywheels. The flywheels define a passage which is surrounded by the atleast one bearing, and the apparatus further comprises means forfastening the first flywheel to a rotary output element of the engine inthe motor vehicle. The fastening means comprises fasteners which areinsertable into holes provided therefor in the first flywheel radiallyoutwardly of the at least one bearing. One side of the first flywheelconfronts the second flywheel and the fasteners are insertable into therespective holes from the one side of the first flywheel. The secondflywheel has openings in at least partial alignment with the holes ofthe first flywheel.

A further feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheelconnectable with the engine of a motor vehicle, a second rotary flywheelwhich is connectable with the transmission of the vehicle by a frictionclutch having a cover, and at least one damper which is operative tooppose rotation of the flywheels relative to each other and is disposedin an annular chamber defined at least in part by one of the flywheelsand disposed radially outwardly of the cover.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheelconnectable to the engine of a motor vehicle, a second rotary flywheelwhich is connectable to the transmission of the vehicle by a frictionclutch having a cover, and at least one damper which is operative tooppose rotation of the flywheels relative to each other and is disposedin an annular fluid-containing chamber defined in part by the firstflywheel and in part by an annular wall which is secured to the firstflywheel, which extends substantially radially inwardly, and whichclosely follows the outlines of energy storing elements forming part ofthe at least one damper and confined in the chamber. The wall and thecover consist of the same material.

A further feature of the invention resides in the provision of a torquetransmitting apparatus comprising a first rotary flywheel which isconnectable with the engine of a motor vehicle, a second rotary flywheelwhich is connectable with the transmission of the vehicle by a frictionclutch having a cover, at least one damper which is operative to opposerotation of the flywheels relative to each other, and at least onewelded joint between the cover and the second flywheel.

An additional feature of the invention resides in the provision of atorque transmitting apparatus which comprises a first rotary flywheelconnectable with the engine of a motor vehicle, a second rotary flywheelconnectable with the transmission of the vehicle by a friction clutch,at least one damper which is operative to oppose rotation of theflywheels relative to each other and is disposed in an annular chamberdefined at least in part by one of the flywheels, and at least onethermal barrier between the second flywheel and the chamber.

Another feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheelconnectable with the engine of a motor vehicle, a second rotary flywheelwhich is connectable with the transmission of the vehicle, at least onedamper which is operative to oppose rotation of the flywheels relativeto each other and includes a plurality of energy storing elements on thefirst flywheel, stressing portions which are rotatable with the secondflywheel and engage the energy storing elements, and at least onethermal barrier which is interposed between the second flywheel and thestressing portions.

A further feature of the invention resides in the provision of a torquetransmitting apparatus which comprises a first rotary flywheelconnectable to the engine of a motor vehicle, a second rotary flywheelconnectable with the transmission of the vehicle by a friction clutchhaving a cover with an axially extending portion which surrounds thesecond flywheel, at least one projection forming part of the axiallyextending portion and received in a radial recess of the secondflywheel, and at least one damper which is operative to oppose rotationof the flywheels relative to each other.

An additional feature of the invention resides in the provision of atorque transmitting apparatus which comprises a first rotary flywheelconnectable with the engine of a motor vehicle, a second rotary flywheelconnectable with the transmission of the vehicle by a friction clutchhaving a cover with an axially extending portion which surrounds thesecond flywheel, a pressure plate which is axially movably connected with the cover, a clutch plate between the second flywheel and thepressure plate, and at least one spring which reacts against the coverand bears against the pressure plate to urge the clutch plate againstthe second flywheel, means for connecting the second flywheel to thecover including at least one substantially cruciform recess in theperipheral surface of the second flywheel and a projection provided onthe axially extending portion of the cover and extending into therecess, and at least one damper which is operative to oppose rotation ofthe flywheels relative to each other.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved apparatus itself, however, both as to construction and its modeof operation, together with additional features and advantages thereof,will be best understood upon perusal of the following detaileddescription of certain presently preferred specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a fragmentary axial sectional view of a torque transmittingapparatus which embodies one form of the invention;

FIG. 2 is a similar fragmentary axial sectional view of a second torquetransmitting apparatus;

FIG. 3 is a smaller-scale axial sectional view of a third apparatus;

FIG. 4 is an axial sectional view of a blank which can be subdividedinto three parts of the torque transmitting apparatus of FIG. 3;

FIG. 5 is a fragmentary axial sectional view of a fourth torquetransmitting apparatus;

FIG. 6 is an enlarged fragmentary sectional view of a detail showing onemode of connecting the cover of the friction clutch to the adjacentflywheel;

FIG. 7 is a view substantially as seen in the direction of arrow VII inFIG. 6;

FIG. 8 is a view similar to that of FIG. 6 but showing a second mode ofconnecting the cover of the friction clutch to the adjacent flywheel;

FIG. 9 is a fragmentary axial sectional view of a detail showing a thirdmode of connecting the cover of the friction clutch with the adjacentflywheel;

FIG. 10 is a fragmentary axial sectional view of a detail showing afurther mode of connecting the cover of the friction clutch to theadjacent flywheel;

FIG. 11 is a view substantially as seen in the direction of arrow XI inFIG. 10;

FIG. 12 is a view substantially as seen in the direction of arrow XII inFIG: 11; and

FIG. 13 is an enlarged fragmentary axial sectional view of a detailshowing a presently preferred sealing element for use as a means forpreventing escape of viscous fluid from the chamber for the damper ordampers of the improved apparatus.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a portion of a torque transmitting apparatus 1 having acomposite flywheel including a first or primary flywheel 2 and a secondor secondary flywheel 3. The flywheel 2 has a substantially disc-shapedradially extending central portion 14 which is connectable to the rotaryelement of an engine, not shown, for example, to the crankshaft of aninternal combustion engine, by fastening means including several rotaryfasteners in the form of screw or bolts 8 (hereinafter called screws forshort). The second flywheel 3 carries a friction clutch 4 which formspart of a power train and can be engaged to transmit torque between theflywheel 3 and the input shaft of a variable-speed transmission, notshown. Reference may be had, for example, to commonly owned U.S. Pat.No. 4,989,710 granted Feb. 5, 1991 to Wolfgang Reik et al. The inputshaft of the transmission receives torque from a clutch plate 5 which isinstalled between a pressure plate 28 of the clutch 4 and an annularradially extending friction surface 32 of the flywheel 3.

An antifriction roller bearing 6 (here shown as a ball bearing with asingle annulus of spherical rolling elements 6a) is installed betweenthe flywheels 2 and 3, and such bearing is disposed radially inwardly ofa set of openings in the form of bores or holes 7 which are provided inthe disc-shaped portion 14 of the flywheel 2 to receive the externallythreaded shanks 40a of the screws 8. The heads 40 of the screws 8 abutthe inner (riqhthand) side of the disc-shaped portion 14 when theflywheel 2 is properly fastened to the rotary output element of theengine.

The apparatus 1 further comprises one or more dampers which opposerotation of the flywheels 2 and 3 relative to each other. FIG. 1 showsonly one damper 9 which includes a set of arcuate energy storingelements 10 in the form of helical springs acting in the circumferentialdirection of the flywheels 2, 3 and being installed in the toroidalradially outermost portion 12 of an annular chamber 11 containing asupply 85 of viscous fluid. The fluid which at least partially fills thechamber 11 is oil or grease and serves to lubricate the energy storingelements 10 as well as several stressing portions or arms 21 formingintegral parts of the cover or housing 22 of the friction clutch 4 andalternating with the energy storing elements 10.

The first flywheel 2 is a suitably shaped and converted blank 13 ofmetallic sheet material which, in addition to the substantially radiallyextending disc-shaped portion 14, includes an axially extending toroidalportion 18 integral with the portion 14 and surrounding the radiallyoutermost portion 12 of the chamber 11, and an axially extending annularprotuberance 15 which is integral with the radially innermost part ofthe disc-shaped portion 14 and is located radially inwardly of the holes7.

The inner race 16 of the bearing 6 surrounds the free end portion orrear end portion 15a of the protuberance 15 of the flywheel 2, and theouter race 17 of this bearing centers and supports the radiallyinnermost portion of the flywheel 3 radially inwardly of the frictionsurface 32. The flywheel 3 is essentially a flat disc-shaped castinghaving an axially extending central passage for the outer race 17 of thebearing 6.

The axially extending portion 18 of the flywheel 2 has a substantiallyC-shaped cross-sectional outline and has an internal surface whichclosely follows the outlines of adjacent portions of the energy storingelements 10. This is particularly important and advantageous in theregions of radially outermost portions of the circumferentiallyextending energy storing elements 10 because each such element can besupported and guided by the adjacent surface of the axially extendingportion 18 when the apparatus 1 is in actual use and the elements 10tend to move radially outwardly under the action of centrifugal force.The portion 18 extends in part forwardly [to the left and hence towardthe engine) and in part rearwardly (to the right) of the plane of theradially extending portion 14. This portion 18 is located radiallyoutwardly of the toroidal outer portion 12 of the annular chamber 11 tothus at least partially surround the energy storing elements 10.

The right-hand end or rear end of the axially extending portion 18 isadjacent the radially outermost portion of a component or wall 19 whichdefines a portion of the chamber 11 and its toroidal portion 12 andcooperates with the portion 18 to properly guide and support at leastthe radially outer portions of the elements 10. The wall 19 can be madeof metallic sheet material, the same as the blank or main portion 13 ofthe flywheel 2. In the apparatus of FIG. 1, the portion 18 and the wall19 are in part mirror images of each other and each thereof definesapproximately or exactly one-half of the toroidal radially outermostportion 12 of the annular space 11. The wall 19 is welded to the portion18, as at 20. The radially inwardly extending portion 19a of the wall 19is adjacent the external surface of an axially extending outer portion23 of the cover 22 and supports a ring-shaped sealing element 31 whichengages the external surface 23a of the portion 23 and constitutes onepart of the means for at least substantially sealing the annular chamber11 and its radially outermost portion 12 from the surroundingatmosphere. The welded joint 20 can constitute a circumferentiallycomplete ring to prevent escape of confined viscous fluid between theaxially extending portion 18 of the flywheel 2 and the wall 19.

The toroidal portion 12 of the chamber 11 is divided into severalcompartments, one for each of the energy storing elements 10. Suchcompartments extend in the circumferential direction of the flywheel 2and alternate with abutments acting as retainers for the adjacentelements 10. The elements 10 are deformed in response to rotation of theflywheel 2 relative to the flywheel 3, or vice versa, by the stressingportions or arms 21 which extend radially of the common axis of theflywheels 2, 3 and into the chamber 11 so as to alternate with theelements 10. Reference may be had, for example, to FIG. 2 of commonlyowned U.S. Pat. No. 4,946,420 granted Aug. 7, 1990 to Johann Jackel. Theportion 18 and/or the wall 19 is provided with internal partitions whichseparate the compartments of the toroidal portion 12 from each other andact as retainers for the respective energy storing elements 10. Eachcompartment can be said to constitute a pocket for the respectiveelement 10, and the elements 10 are stressed by the arms 21 when atleast one of the flywheels 2, 3 changes its angular position relative tothe other flywheel. The stressing arms 21 are provided on the cover 22of the friction clutch 4, and more particularly on the portion 23 of thecover. The stressing arms 21 which are shown in FIG. 1 are radiallyoutwardly extending fingers which are integral with the axiallyextending portion 23 of the cover 22 and extend into the toroidalportion 12 of the annular chamber 11 in the general plane of thedisc-shaped portion 14 of the flywheel 2. As mentioned above, thestressing arms 21 engage the adjacent energy storing elements 10 in thetoroidal portion 12 of the chamber 11 and cause such elements to storeenergy when the flywheel 2 and/or 3 leaves its neutral or startingangular position relative to the other flywheel.

The axially extending portion 23 of the cover 22 is adjacent andsurrounds the peripheral surface of the flywheel 3 and is non-rotatablyand rigidly connected thereto by a set of projections or lobes 24provided on the portion 23 and extending into complementary notches orrecesses in the peripheral surface of the flywheel 3. In order tofacilitate proper axial positioning of the flywheel 3 and frictionclutch 4 relative to each other, the internal surface of the axiallyextending portion 23 is provided with a circumferentially extendingshoulder 25 for the adjacent radially outermost portion of the flywheel3. The projections 24 are formed at a time when the flywheel 3 alreadyabuts the shoulder 25.

The cover 22 of the friction clutch 4 is accurately centered when itsaxially extending portion 23 engages the peripheral surface of theflywheel 3 and the latter abuts the internal shoulder 25 of the portion23. The portion 23 is integral with the radially outermost part of asubstantially radially extending portion 26 of the cover 22, and theportion 26 carries rivets 26a for two ring-shaped seats 26b, 26cflanking the circumferentially complete annular portion of a diaphragmspring 27 having radially inwardly extending prongs 27a. The diaphragmspring 27 acts not unlike a two-armed lever and its annular outerportion normally bears against the adjacent projections of the axiallymovable pressure plate 28 which is non-rotatably connected to but ismovable axially of the cover 22. The pressure plate 28 is adjacent oneof two friction linings 29 on the flange-like carrier 41 of the clutchplate 5. The latter further comprises a hub which is integral with theradially innermost portion of the carrier 41 and can be non-rotatablyslipped onto the input shaft of a variable-speed transmission. The hubfor the carrier 41 is partially surrounded by the free end portion 15aof the protuberance 15 and extends into the central axial passage whichis defined by the flywheel 2. The other friction lining 29 on thecarrier 41 of the clutch plate 5 is adjacent the friction surface 32 ofthe fl.vwheel 3. When the friction clutch 4 transmits torque between theflywheel 3 and the variable-speed transmission of the vehicle, thefriction linings 29 of the clutch plate 5 are clamped between thefriction surface 32 of the flywheel 3 and the adjacent surface of thepressure plate 28 which is biased by the diaphragm spring 27. In orderto disengage the clutch 4, the prongs 27a of the diaphragm spring aremoved to the left so that the radially outermost portion of thediaphragm spring 27 relaxes the bias upon the pressure plate 28 and thelatter is pulled to the right by leaf springs or the like (not shown) onthe cover portion 23 or 26 to relax the pressure upon the adjacentfriction lining 29. This enables the flywheel 3 to rotate independentlyof the clutch plate 5 and vice versa.

FIG. 1 shows that by far the major part of the annular chamber 11(including the entire toroidal portion 12) is located radially outwardlyof the second flywheel 3. This renders it possible to mount the flywheel3 in immediate or close proximity to the disc-shaped portion 10 so thatthe flywheels 2, 3 define a substantially radially extending narrowclearance or gap 30, and such clearance extends practically all the wayfrom the protuberance 15 to the portion 23 of the cover 22. At least asubstantial part of the flywheel 3 is actually surrounded by the chamber11, and the entire flywheel 3 is located radially inwardly of suchchamber. This renders it possible to significantly enhance thecompactness of the improved torque transmitting apparatus, particularlyin the axial direction of the flywheels 2 and 3. Such torquetransmitting apparatus can be utilized with advantage in all types ofmotor vehicles including those wherein the engine-transmission assemblyextends in the direction of movement of the vehicle as well as invehicles wherein the engine-transmission assembly extends transverselyof such direction.

As can be seen in FIG. 1, the combined axial length of the flywheels 2,3, bearing 6, damper 9 and friction clutch 4 is a small fraction of thediameter of the flywheel 2. This is of considerable importance in manymotor vehicles which provide space for a larger-diameter flywheel-clutchunit but little room in the axial direction of such unit. The entiresecond flywheel 3 is closely or immediately adjacent the converted blank13 of the flywheel 2. In fact, if the wall 19 is considered an integralpart of the flywheel 2, this flywheel confines the outer flywheel 3 sothat only the friction clutch 4 projects axially beyond the primaryflywheel. The flywheel 3 need not even participate in sealing of thechamber 11 from the atmosphere. The aforementioned sealing means for thechamber 11 includes the sealing element 31 which surrounds the axiallyextending portion 23 of the cover 22, and a ring-shaped seal 36 whichoperates between the flywheel 2 (at the junction of the disc-shapedportion 14 and axially extending portion 18) and an internal shoulder 37of the axially extending portion 23 of the cover 22 adjacent theprojections 24. The improved apparatus is designed in such a way thatnone of the component parts of the friction clutch 4 and/or any otherparts extend between the flywheel 3 and the adjacent portion of theflywheel 2.

It is presently preferred to design and mount the flywheels 2 and 3 insuch a way that the width of 50% or more of the clearance 30 (as seen inthe axial direction of the flywheels 2 and 3) is in the range of 0.5 to4 mm. Highly satisfactory results were obtained with a torquetransmitting apparatus wherein the width of the clearance is between 1and 2 mm. The clearance 30 can be used to establish a portion of a pathfor the flow of a cooling medium, such as air, which prevents thetransfer of heat from the friction surface 32 of the flywheel 3 to theflywheel 2. Actually, the stream or streams of air flowing through theclearance 30 cool the entire apparatus including the flywheels 2 and 3,the bearing or bearings 6, the parts which define the chamber 11, andthe friction clutch 4. The radially inner portion of the flywheel 3 hasone or more openings or holes 33 which constitute inlets for admissionof cool atmospheric air into the clearance 30, and the radially outerportion of the flywheel 3 has one or more openings or holes 35 which actnot unlike an outlet for the air stream or air streams flowing radiallyoutwardly along the inner side of the disc-shaped portion 14. The lattercan be provided with one or more openings 34 which are disposed radiallyoutwardly of the openings 33 and can discharge some air in a directiontoward the engine. The openings 33, 34 are located radially inwardly,and the openings 35 are located radially outwardly of the frictionsurface 32 on the flywheel 3. The circulation of air, and hence thecooling action of such air, can be improved still further by providingone or more openings or ports 38 in the axially extending portion 23 ofthe cover 22. Jets of cooling air which are admitted into the clearance30 by the openings 33 of the flywheel 3 impinge directly against theradially inner part of the disc-shaped portion 14, and such jets removeheat from the region around the bearing 6.

The openings 33 can be provided in addition to or in lieu of theopenings 34, and the openings 33 can serve the additional purpose ofpermitting introduction of the shanks 40a of screws 8 (each such screwcan constitute an allen screw) into the holes 7 of the disc-shapedportion 14. Moreover, the openings 33 enable the working end of a tool(not shown) to reach the heads 40 of the screws 8 and to rotate thescrews, either in a direction to drive the shanks 40a home into thetapped bores or holes of the output element of the engine or to separatethe flywheel 2 from such output element.

The openings 33, 34, 35 and/or the parts 38 can be round or can resembleslots which preferably extend in the circumferential direction of theflywheels 2 and 3.

The ring-shaped seal 36 in the radially outermost portion of theclearance 30 can include or constitute a diaphragm which seals theclearance 30 from the chamber 11. It is also possible to employ a seal36 which resembles or constitutes a diaphragm spring. The seal 36 islocated, at least in part, radially outwardly of the friction surface32. This seal can be provided further radially inwardly but preferablynot beyond a location halfway between the radially innermost andradially outermost portions of the friction surface 32. Thus, at leastthe inner half of the friction surface 32 is located radially inwardlyof the radially inwardly extending portion of the chamber 11 immediatelyadjacent the seal 36.

It is presently preferred to secure the radially innermost portion ofthe seal 36 to the flywheel 2 and to cause the radially outermostportion of this seal to bear against the internal shoulder 37 of theaxially extending portion 23 of the cover 22. The shoulder 37 centersthe seal 36 in an optimum position to prevent communication between theradially inner portion of the chamber 11 and the radially outermostportion of the clearance 30. The seal 36 is installed in prestressedcondition and is shown at the general level of the openings 35 in theradially outermost portion of the flywheel 3.

The sealing element 31 can constitute an O-ring or a solid ring ofrubber or other suitable elastomeric material. This ring is recessedinto the inner end face of the radially inwardly extending portion 19aof the wall 19 and is in sealing engagement with the external surface23a of the axially extending portion 23 of the cover 2. If desired, theillustrated sealing element 31 can be replaced with a diaphragm spring,with a membrane or with any other part which can reliably prevent escapeof viscous fluid from the annular chamber 11. The placing of sealingmeans 31, 36 at or radially outwardly of the flywheel 3 ensures that theflywheels 2, 3 can define a large clearance or gap 30 which, in turn,ensures highly satisfactory circulation of large quantities of coolingatmospheric air to prevent overheating of the viscous fluid, of thebearing 6, of the flywheels and/or the engine. Heat is generatedprimarily at the friction surface 32 of the flywheel 3; therefore,circulation of large quantities of air, with attendant thorough coolingof the flywheel 3, is highly desirable.

It will be noted that the openings 35 in the flywheel 3 are locatedradially inwardly of the sealing element 31. These openings enablestreams of air to flow along the internal surface of the axiallyextending portion 23, of the cover 22 and to remove heat from thepressure plate 28 and diaphragm spring 27. The ports 38 in the axiallyextending portion 23 promote the flow of air into and from the clearance30 and along the internal surface of the portion 23. It is presentlypreferred to install the seal 36 at the level of openings 35 and of theradially outermost portion of the friction surface 32 (as seen in theradial direction of the flywheels 2, 3 from their common axis toward theannular chamber 11).

The wall 19 further serves as a carrier of a starter gear 39 which issecured to it by a circumferentially complete welded seam or by spotwelding.

The flywheels 2, 3 and the friction clutch 4 including the parts 5, 22,27 and 28 are connected together to form a preassembled unit A which canbe easily manipulated in storage, during shipment as well as duringattachment to the output element of an engine. In order to assemble theunit A, the flywheel 3 is connected with the clutch 4 in a first step insuch a way that the friction linings 29 of the clutch plate 5 arelocated between the friction surface 32 and the pressure plate 28. Thethus obtained subassembly is then properly combined with the flywheel 2which involves introducing the stressing arms 21 into the chamber 11between the energy storing elements 10 of the damper 9 prior toapplication of the wall 19 which is thereupon welded to the axiallyextending portion 18 of the flywheel 2 to complete the assembly of theunit A. The wall 19 can be slipped onto the axially extending portion 23of the cover 22 in a direction from the right, as seen in FIG. 1. Theenergy storing elements 10 are introduced into the toroidal portion 12of the chamber 11 prior to welding of the wall 19 to the flywheel 2, asat 20. The sealing element 31 is inserted into the recess of theradially extending portion 19a of the wall 19 before the latter isslipped onto the external surface of the axially extending portion 23 ofthe cover 22, and the seal 36 is affixed to the inner side of theflywheel 2 before the flywheel 3 is moved to the illustrated position inwhich the two flywheels define the large radially extending clearance orgap 30. The bearing 6 is mounted first on the protuberance 15 of theflywheel 2 or in the axial passage of the flywheel 3.

The screws 8 are inserted into the holes 7 of the flywheel 2 before thelatter is assembled with the flywheel 3 and clutch 4. The heads 40 ofthe screws 8 extend into the openings 33 of the flywheel 3 but thescrews cannot be lost of displaced because their shanks 40a areprevented from leaving the respective openings or holes 7 by the clutchplate 5. The carrier 41 of the clutch plate 5 is provided with openingsor holes 43 having diameters which are smaller than the diameters of theheads 40. Alternatively, or in addition to such dimensioning of theholes 43 in the carrier 41 of the clutch plate 5, the diameters of theopenings or holes 44 in some or all of the prongs 17a are smaller thanthe diameters of the heads 40 so that the screws 8 are maintained inpositions of readiness to be driven into the tapped pores or holes ofthe output element of the engine by the working end of a suitable toolwhich is introduced through a hole 44 of one of the prongs 27a, througha hole 43 in the carrier 41 of the clutch plate 5, through an opening 33and into the polygonal (normally hexagonal) socket in the head 40 of therespective screw 8. The space which is defined for each screw 8 betweenthe inner side of the disc-shaped portion 14 and the left-hand side ofthe carrier 41 in the assembled unit A suffices to ensure that the tipsof shanks 40a of the screws 8 need not extend beyond the left-hand side42 of the radially innermost part 14a of the portion 14 duringinstallation of the unit A in a motor vehicle prior to actual attachmentof the flywheel 2 to the output element of the engine. To this end, theradially innermost part 14a of the disc-shaped portion 14 can bulgeoutwardly and away from the adjacent portion of the flywheel 3.

Yieldable elastic rings, sleeves, tongues or like parts can be providedbetween the outer side 42 of the disc-shaped portion 14 and the carrier41 to accurately locate the screws 8 for convenient rotation by a toolin order to drive the shanks 40a into the tapped bores or holes of theoutput element of the engine during installation of the torquetransmitting apparatus 1 in a motor vehicle. The yieldable parts undergodeformation and/or are pushed aside while the screws 8 are being drivenhome by a suitable tool. For example, the yieldable elastic orientingand retaining means for the screws 8 can include rubber sleeves whichare introduced into the holes 7 to receive and surround the shanks 40aof the respective screws 8. Such sleeves are expelled from the holes 7or simply yield when the screws begin to move axially in order topenetrate into the aligned tapped bores of the output element of theengine. The sleeves in the holes 7 hold the shanks 40a in such positionsthat they normally do not extend outwardly beyond the left-hand side 42of disc-shaped portion 14 of the flywheel 2. This simplifies properpositioning of the unit A for attachment to the engine. If desired, theelastic sleeves can be slipped onto the shanks 40a prior to introductionof the tips of such shanks into the respective holes 7.

The clutch plate 5 of the preassembled unit A is centered by theflywheel 3 and pressure plate 28 in such position that its axiscoincides with the axis of the output element of the engine when theflywheel 2 is connected to the engine. The angular position of theclutch plate 5 in the unit A is selected in such a way that each opening33 of the flywheel 3 is in at least partial alignment with a hole 43 ofthe carrier 41. The extent of alignment of holes 43 with the openings 33should be sufficient to permit convenient introduction of a wrench orany other suitable tool which is used to drive the screws 8 home.

The diaphragm spring 27 is mounted in the cover 22 of the frictionclutch 4 in such a way that each opening 33 of the flywheel 3 is inpartial or full alignment with one of the holes 44. Thus, the torquetransmitting tool can be introduced first through a hole 44, thereuponthrough a hole 43 and thereupon into the socket of the respective head40 in order to transmit torque in a direction such that the screw 8 issecured in the output element of the engine. The holes 44 in the prongs27a of the diaphragm spring 27 can constitute circular holes which arecompletely surrounded by the material of the respective prongs 27a, orlateral recesses or notches or cutouts in the respective prongs.Reference may be had to commonly owned U.S. Pat. No. 4,747,586 grantedMay 31, 1988 to Wolfgang Reik. All that counts is to ensure that atorque transmitting tool can be moved into proper engagement with theheads 40 of the screws 8, either for the purpose of affixing the unit Ato an engine or for the purpose of disconnecting such unit from theengine. For example, the holes 44 can constitute enlarged portions ofslots which alternate with the prongs 27a of the diaphragm spring 27.

Care should be taken to ensure that, when the unit A is assembled, eachhole 7 is in proper or adequate alignment with an opening 33, with ahole 43, and with a hole 44 even if the holes 7 are not equidistant fromeach other. Such unequal distribution of holes 7 in the innermost part14a of the disc-shaped portion 14 in the region outwardly adjacent theprotuberance 15 is often desirable and advantageous when it is necessaryto ensure that the flywheel 2 can be affixed to the output element ofthe engine in a single predetermined angular position. Reference may behad, for analogy, to commonly owned U.S. Pat. No. 4,493,409 granted Jan.15, 1985 to Klaus Steeg.

The holes or slots or recesses 44 are smaller than necessary to permitthe passage of the heads 40.

The assembly of improved apparatus 1 into a unit A which is ready to beaffixed to an engine and to a transmission facilitates the task ofinstalling the apparatus in a motor vehicle and brings about substantialsavings in time. For example, it is much simpler (a) to properly centerall component parts (particularly the clutch plate 5) prior toattachment to an engine, (b) to install the clutch plate 5 between thecover 22 of the friction clutch 4 and the flywheel 3, (c) to attach thefriction clutch 4 to the flywheel 3, (d) to introduce the customarycentering mandrel, (e) to center the clutch plate 5 on the mandrel, (f)to insert the screws 40, (g) to actually attach the flywheel 2 to theoutput element of the engine, and (h) to withdraw the centering mandrel.

An important advantage of the improved apparatus is that it can dispensewith the flange (note the flange 32 in FIG. 1 of the aforementionedcommonly owned U.S. Pat. No. 4,989,710) which is a standard part ofpresently known torque transmitting apparatus, which serves to transmittorque from the energy storing elements of the damper or dampers to thesecondary flywheel, and which is disposed between the primary andsecondary flywheels. Consequently, the two flywheels can be moved intoimmediate or very close proximity to each other to thus contribute to areduction of the axial dimensions of the improved apparatus. Thefunction of the conventional flange is taken over by the stressing arms21 which are preferably (but need not be) integral parts of the cover22. Thus, the primary flywheel 2 transmits torque to the secondaryflywheel 3 by way of the damper 9, stressing arms 21 and cover 22 of thefriction clutch 4.

If the stressing arms 21 are not integral with the cover of the frictionclutch (FIG. 2), the two flywheels can be fully assembled with oneanother before the secondary flywheel is connected with the cover of thefriction clutch. Such design of the improved apparatus exhibits theadditional advantage that the clutch can employ a standard cover whichis separably connected with the carrier of stressing arms or withdiscrete stressing arms.

The flywheels 2 and 3 can be positioned in immediate or close proximityto each other because the annular chamber 11 is moved radially outwardlybeyond the peripheral surface of the secondary flywheel. As mentionedabove, the seal 36 can be located radially outwardly of the frictionsurface 32 of the secondary flywheel 3 and is preferably mounted in sucha way that it does not extend radially inwardly beyond a positionsubstantially halfway between the radially innermost and outermostportions of the friction surface 32. In other words, the radiallyinnermost portion of the chamber 11 should not be located nearer to theradially innermost portion than to the radially outermost portion of thefriction surface 32.

The disc-shaped portion 14 of the primary flywheel 2 is or can beimmediately adjacent the output element (e.g., a crankshaft) of theengine which is to rotate the flywheel 2. Such mounting of the flywheel2 also contributes to a reduction of space requirements of the apparatusas seen in the axial direction of the output element of the engine.

In the apparatus of FIG. 1, the disc-shaped portion 14 of the primaryflywheel 2 extends radially outwardly all the way to the radiallyoutermost portion of the friction surface 32 on the secondary flywheel3. This is desirable and advantageous because the secondary flywheelneed not extend radially outwardly beyond the disc-shaped portion and atleast the major part of the secondary flywheel can be placed into closeor immediate proximity to the primary flywheel. The arrangement ispreferably such that the disc-shaped portion 14 extends radiallyoutwardly to a position at least midway between the radially innermostand radially outermost portions of the friction surface 32.

When the wall 19 is welded to the axially extending portion 18 of theprimary flywheel 2, the latter can be said to resemble a rather shallowreceptacle which fully or nearly fully accommodates the secondaryflywheel 3. The latter is located radially inwardly of the annularchamber 11 and is aligned with the chamber in the axial direction of thetwo flywheels.

The positioning of the bearing 6 in the general plane of the secondaryflywheel 3 also contributes to compactness of the apparatus 1. Theright-hand end faces of the races 16, 17 are located in or close to theplane of the friction surface 32. In other words, the secondary flywheeldoes not extend, or need not appreciably extend, beyond the frictionsurface 32 (as seen in a direction away from and axially of the primaryflywheel 2).

The radially innermost portion 19a of the wall 19 is located radiallyoutwardly of the peripheral surface of the secondary flywheel 3 andradially outwardly of the axially extending portion 23 of the cover 22.This is desirable and advantageous for the aforediscussed reasons, i.e.,the secondary flywheel 3 can be introduced into the axially extendingportion 23 and the latter can be introduced into the space within theportion 19a so that the flywheel 3 can be moved into immediate or closeproximity to the disc-shaped portion 14 of the flywheel 2 and can be atleast partially surrounded by the chamber 11.

It is presently preferred to design and assemble the flywheels 2 and 3in such a way that the disc-shaped portion 14 overlies at least theinner half of the flywheel 3 (as seen from the common axis of theflywheels toward the chamber 11). Thus, the clearance 30 preferablyextends radially outwardly from the radially innermost portion of thesecondary flywheel and to a location at least substantially midwaybetween the radially innermost and outermost portions of the frictionsurface 32. This requirement is more than met in the apparatus of FIG. 1since the clearance 30 extends radially outwardly all the way to or atleast in close proximity of the radially outermost portion of thefriction surface 32.

The ring-shaped starter gear 39 can constitute an integral part of thewall 19. This contributes to lower cost of the apparatus because thegear 39 need not be welded or otherwise nonrotatably secured to the wall19. The illustrated gear 39 is substantially coplanar with the clutchplate 5, i.e., the friction linings 29 are spaced apart from thedisc-shaped portion 14 of the primary flywheel 2 a distance which equalsor approximates the distance of the gear 39 from the plane of theportion 14. The illustrated gear 39 is spaced apart from the axiallyextending portion 23 of the cover 22 as seen in the radial direction ofthe apparatus. This gear is located at the level of that (substantiallyaxially extending) portion of the wall 19 which surrounds approximatelyone-half of the toroidal portion 12 of the annular chamber 11.

As can be seen in FIG. 1, the stressing arms 21 can extend radiallyoutwardly and substantially diametrically of the adjacent energy storingelements 10 from locations substantially radially inwardly of the arms21 and radially outwardly to locations at or close to the radiallyoutermost portions of the arms. In other words, that portion of each arm21 which engages the adjacent energy storing element 10 can have alength which at least approximates the diameter of an energy storingelement. As mentioned above, and as will be described in greater detailwith reference to FIG. 3, the stressing arms cooperate with retainerswhich are mounted on, or form part of, the primary flywheel so that theenergy storing elements 10 are stressed by being compressed between therespective arms 21 and the corresponding retainers of or on the flywheel2 when at least one of the flywheels is caused to turn relative to theother flywheel.

The provision of holes 7 radially outwardly of the bearing 6 ispreferred in many instances. However, and as will be described withreference to FIG. 5, the holes for the screws which fasten the primaryflywheel to the engine can be provided at a level such that one of theraces of the bearing must be formed with holes in register with holes inthe primary flywheel. It is equally possible to provide holes for screws8 radially inwardly of the bearing 6 or to provide some holes radiallyinwardly and some holes radially outwardly of the bearing. An advantageof positioning the bearing radially inwardly of the holes 7 is that theapparatus can employ a smaller and less expensive bearing.

The openings 33 in the secondary flywheel 3 are or can be sufficientlylarge to permit passage of the heads 40. This is desirable andadvantageous if the screws 8 are to be introduced into the holes 7subsequent to assembly of the flywheel 2 with the flywheel 3.

If the mutual spacing of neighboring holes 7 in the disc-shaped portion14 of the primary flywheel 2 is only slightly non-uniform (such as issufficient to ensure that the flywheel 2 can be affixed to the outputelement of the engine in a single predetermined angular position inwhich each hole 7 is in accurate register with a discrete tapped bore inthe output element), the mutual spacing of the openings 33 and/or holes43 and/or holes 44 can be uniform. All that counts is to ensure that,when the unit A is assembled and is ready to be affixed to the outputelement of an engine, the holes 44, 43 and the openings 33 are inadequate alignment with the heads 40 of the respective screws 8 so thatthe heads can be engaged by the working end of a rotary tool which isused to drive the shanks 40a into the tapped bores of the outputelement. If the mutual spacing of the holes 7 is not entirely uniform(as seen in the circumferential direction of the bearing 6) and themutual spacing of the openings 33 and/or holes 43 and/or holes 44 isuniform, the diameters of the openings 33 and/or holes 43 and/or holes44 must be larger than the diameter of that portion of the tool which isto be introduced through the holes 44, 43 and openings 33 in order toreach the heads 40 of the screws 8 which are confined in the spacebetween the disc-shaped portion 14 and the carrier or flange 41 of theclutch plate 5. Nevertheless, the diameters of the holes 43 and/or 44should be smaller than the diameters of the heads 40 so that thefasteners cannot escape from the aforementioned space even if the unit Alies flat so that the radially extending portion 26 of the cover 22constitutes the lowermost part of the unit. The holes 44 can berelatively large if the holes 43 are sufficiently small to preventpassage of the heads 40. Inversely, the holes 43 can be relatively largeif the holes 44 are too small to prevent the passage of heads 40.

Assembly of the flywheels 2, 3, bearing 6, damper 9 and friction clutch4 into a unit A which is ready to be stored, transported or mounted doesnot present problems when the properly installed apparatus 1 must bepartially dismantled for inspection and/or for other reasons, forexample, to replace worn or damaged friction linings 29 (together withthe clutch plate 5), especially if the apparatus is assembled in amanner to be described with reference to FIG. 2, namely when thefriction clutch comprises a cover (e.g., a standard cover) which is notdirectly connected to the secondary flywheel. In the modified apparatusof FIG. 2, the axially extending portion of the clutch cover does notcontact the viscous fluid in the annular chamber for the damper ordampers. In the apparatus of FIG. 1, the axially extending portion 23 ofthe cover 22 bounds the radially inner portion of the chamber 11 andcooperates with the seal 36 to establish a liquid-impermeable barrierbetween the radially inner portion of the chamber 11 and the adjacentoutermost portion of the clearance 30.

The torque transmitting apparatus 101 of FIG. 2 differs from theapparatus 1 mainly in the design of the cover 122 of the friction clutch104, in the design of the clutch plate 105, and in the manner ofmounting the stressing arms 121 on the cover 122. All such parts of theapparatus 101 which are identical with or clearly analogous tocorresponding parts of the apparatus 1 are denoted by similar referencecharacters plus 100.

The first or primary flywheel 102 of the torque transmitting apparatus101 is practically identical with the flywheel 2 except that theopenings or holes 134 are more distant from the common axis of theflywheels 102, 103 and are located opposite the radially outer half offriction surface 132 of the flywheel 103. The antifriction ball, rolleror needle bearing 106 surrounds the axial protuberance 115 on theflywheel 102 and supports the flywheel 103 radially inwardly of theopenings or holes 133 for the screws 108. The hub 152 of the clutchplate 105 has a front end portion 151 which extends into the interior ofthe protuberance 115. The hub 152 is internally splined so that it canbe non-rotatably slipped onto the input shaft of a variable-speedtransmission (not shown) in such a way that a portion of the input shaftextends into a pilot bearing 153 within the annular protuberance 115.The flange or carrier 141 of the clutch plate 105 includes a conicalintermediate portion so that the friction linings 129 are axially offsetrelative to the radially innermost portion of the carrier 141. Thefriction linings 129 are installed between the friction surface 132 ofthe flywheel 103 and the axially movable pressure plate 128 which isnon-rotatably but axially movably mounted on the cover 122. The pressureplate 128 can be biased against the adjacent friction lining 129 of theclutch plate 105 by a diaphragm spring 127 which is mounted on theradially extending portion of the cover 122 in the same way as describedin connection with the diaphragm spring 27 of FIG. 1.

The main portion 113 of the fly-wheel 102 includes the disc-shapedportion 114 which carries the protuberance 115 and has holes or bores107 for the shanks of the screws 108 as well as the openings 134. Theradially outermost part of disc-shaped portion 114 of the main portion113 is integral with the axially extending portion 118 which is weldedto a component 119 (hereinafter called wall) corresponding substantiallyto the wall 19 and being sealingly engaged by the sealing element 131.The wall 119 carries a ring-shaped starter gear 139 and cooperates withthe axially extending portion 118 to surround the toroidal radiallyoutermost portion 112 of the annular chamber 111 for the energy storingelements 110 of the damper 109.

The protuberance 115 is a separately produced part which is welded orotherwise reliably secured to the disc-shaped portion 114 of theflywheel 102. The axial passage 150 of the protuberance 115 accommodatesthe pilot bearing 153 and the aforementioned front end portion 151 ofthe hub 152, i.e., of the radially innermost portion of the clutch plate105. The pilot bearing 153 is or can be mounted within the bearing 106as seen in the axial and radial directions of the protuberance 115.

The pilot bearing 153 can be installed directly in the rotary inputelement (not shown) of the engine which is to rotate the flywheel 102.The length of the input shaft of the variable-speed transmission of themotor vehicle is then selected in such a way that the input shaftextends to the left through the entire passage 150 and into a socket inthe front end face of the output element. The latter then serves as ameans for centering the free end portion of the input shaft.

The apparatus 101 of FIG. 2 also comprises means for preventingdisplacement or loss of screws 108 once the flywheels 102, 103, thebearing 106, the clutch plate 105, the remaining parts of the frictionclutch 104, and the damper 109 are assembled into a unit correspondingto the unit A of FIG. 1. Such unit can be readily transported intostorage, from storage to the locale of use, at the locale of use andduring attachment to the output element of an engine.

The stressing arms 121 for the energy storing elements 110 of the damper109 extend radially outwardly as well as forwardly from a ring-shapedcomponent 156 (hereinafter called ring) which is affixed to the radiallyoutermost portion 159 of the cover 122 by a set of screws or bolts 158and/or other suitable fasteners. The ring 156 has a radially innermostportion 157 which is welded to a circumferentially complete annularmember 155. The stressing arms 121 are integral with the member 155;they become effective to cause the elements 110 to store additionalenergy when at least one of the flywheels 102, 103 changes its angularposition relative to the other flywheel. The ring 156 has asubstantially L-shaped cross-sectional outline and, in addition to theradially innermost portion 157, comprises a radially outwardly extendingportion 156a which is adjacent the portion 159 of the cover 122 and issecured thereto by the bolts 159.

The torque transmitting apparatus 101 further comprises a membrane 160having an outer marginal portion 161 which is sealingly clamped betweenthe portion 156a of the ring 156 and the portion 159 of the cover 122,an intermediate portion 162 which is fixedly secured to the peripheralsurface of the flywheel 103, and a radially innermost portion 164 whichoverlies the left-hand side of the flywheel 103 in the clearance or gap130 between the two flywheels. The intermediate portion 162 of themembrane 160 has projections 163 which are received in complementarydepressions or recesses in the peripheral surface of the flywheel 103.The membrane 160 serves as a means for connecting the cover 122 of thefriction clutch 104 to the flywheel 103. The portions 161, 164 of themembrane 160 extend substantially radially of the flywheels 102, 103,and the intermediate portion 162 extends substantially axially of thefriction linings 129 and flywheel 103.

The left-hand side of the flywheel 103 is formed with one or moreventilating and flushing channels 165 which extend (or can extend)substantially radially of the flywheels and are overlapped by theradially innermost portion 164 of the membrane. The channels 165 canconstitute grooves which are machined into or are otherwise formed inthe left-hand side of the flywheel 103. The latter is further providedwith one or more substantially axially extending passages (air admittinginlets) 166 radially inwardly of the friction surface 132 and of thefriction linings 129, and with one or more substantially axiallyextending passages (air discharging outlets) 167 for spent air which hasbeen caused to flow through the respective channel 165. The outlets 167are located radially outwardly of the friction surface 132 and frictionlinings 129 and are immediately or closely adjacent the substantiallyaxially extending intermediate portion 162 of the membrane 160.

The flywheel 103 can be cooled by air streams which flow in the channels165 as well as by air streams which enter the clearance 130 at theleft-hand side of the radially innermost portion 164 of the diaphragm160 by way of openings 133 in the flywheel 103 and leave the clearance130 by way of openings 134 in the disc-shaped portion 114 of theflywheel 102. The openings 133 further serve to afford access to thescrews 108 as well as to facilitate introduction of the shanks of suchscrews into the registering holes 107 of the flywheel 102. The openings134 are closely or immediately adjacent the seal 136 which preventscommunication between the clearance 130 and the radially inner portionof the annular chamber 111. The seal 136 can constitute or include adiaphragm spring which is affixed to the member 155 and bears againstthe right-hand side of adjacent portion of the flywheel 102 or viceversa. The illustrated seal 136 is located at the level of theperipheral surface of the flywheel 103 (as seen in a direction from thecommon axis of the flywheels toward the annular chamber 111).

The sealing element 131 can constitute a diaphragm spring or a membraneand is installed between the member 155 and the wall 119, i.e., betweenthe flywheel 102 and the cover 122 of the friction clutch 104. It isoften advisable to design the sealing element 131 in such a way that itincludes a radially extending portion which is sealingly receivedbetween the member 155 and the portion 157 of the ring 156. The member155 is thereupon welded to the portion 157 of the ring 156 to ensurehighly reliable sealing engagement of the sealing element 131 with thering portion 157 as well as with the member 155.

The membrane 160 performs the additional function of centering thestressing arms 121, their supporting member 155 and the portion 157 ofthe ring 156 on the flywheel 103.

An advantage of the membrane 160 is that it can serve as a means forcentering the cover 123 on the secondary flywheel 103 in the radialdirection and that it can also locate the cover relative to thesecondary flywheel in the axial direction of the two flywheels. Themembrane contributes to compactness of the apparatus 101 because itsthickness can be but a small fraction of the thickness of metallic sheetmaterial of the cover 122. Since the projections 163 establishconnections which prevent radial and axial movements of the secondaryflywheel 103 and the intermediate portion 162 of the membrane 160relative to each other, the membrane constitutes the means fortransmitting torque from the primary flywheel 102 to the secondaryflywheel.

Another advantage of the membrane 160 is that it performs the functionof a thermal insulator or thermal barrier between the secondary flywheel103 on the one hand and the viscous fluid and energy storing elements110 in the annular chamber 111 on the other hand. The channel orchannels 165 also contribute to removal of heat from the secondaryflywheel 103 so that the latter is less likely to transmit excessivequantities of heat to the contents of the chamber 111.

The channel or channels 165 are provided in that (front) side of thesecondary flywheel 103 which faces away from the clutch 104 and awayfrom the friction surface 132. This is desirable and advantageousbecause the channel or channels 165 can be formed in the mold which isused to make the flywheel 103. The aforedescribed undertakings forcooling the secondary flywheel 3 or 103 can be used jointly orindependently of each other, depending on the desired or necessaryextent of cooling.

The cooling action can be enhanced still further by providing thepressure plate 128 with one or more radially and/or otherwise extendingventilating channels. Such channels can be provided in that side of thepressure plate 128 which faces away from the clutch plate 105 andsecondary flywheel 103. If the pressure plate 128 is a casting, theventilating channels in its right-hand side can be formed in the mold,the same as described in connection with the ventilating channels 165 inthat side of the secondary flywheel 103 which faces away from thefriction surface 132. The channels 165 and the channels of the pressureplate 128 can be said to constitute grooves which preferably extendsubstantially radially of the respective parts. The length of channels165 preferably at least equals or exceeds the width of the frictionsurface 132 (as measured radially of the secondary flywheel 103), andthe length of radial channels in the pressure plate 128 preferably atleast matches or exceeds the width of the friction surface of thepressure plate, i.e., of that surface which bears upon the adjacentfriction lining 129 when the friction clutch 104 is engaged.

It is equally possible to provide the secondary flywheel 103 withchannels 165 which are straight but do not extend substantially radiallyof this flywheel and/or with arcuate and/or otherwise configuratedchannels which may but need not extend substantially radially. The sameapplies for the channels (if any) in the pressure plate 128.

The protuberance 115 can constitute a separately produced sleeve or apiece of pipe which is welded to the primary flywheel 103 and definesthe passage 150 for the input element of the variable-speedtransmission.

The apparatus of FIG. 2 can be modified by employing a protuberancewhich is an integral part of or which is secured to the secondaryflywheel. Still further, at least one protuberance can be provided oneach of the two flywheels and the antifriction bearing or bearings canbe disposed between the protuberances of the two flywheels.

In most instances, the protuberance is preferably provided on thatflywheel (2 or 102) which defines a portion of or the entire annularchamber (11 or 111) for one or more dampers.

The protuberance 115 of FIG. 2 can constitute the inner race of thebearing 106. The outer race of this bearing is inwardly adjacent or isformed by the radially innermost portion of the membrane 160. Thefeature that one of the races is an integral part of one of theflywheels contributes to simplicity and compactness of the apparatus.

FIG. 3 shows certain details of a third torque transmitting apparatus201 wherein all such parts which are identical with or clearly analogousto corresponding parts of the apparatus 1 of FIG. 1 are denoted bysimilar reference characters plus 200. The flywheel 202 is connectablewith the rotary input element of a combustion engine (not shown) in thesame way as described in connection with FIG. 1. One of a set of screws208 (namely the upper screw of FIG. 3) is shown in extended position [asif driven into a tapped bore or hole of the output element) and issurrounded by a yieldable sleeve-like element 208 which ensures that theshank of this screw remains in the respective hole 207 in a given axialposition unless intentionally displaced as a result of rotation by asuitable tool, not shown. The other (lower) screw 208 is shown in aposition of readiness in which its shank does not project to the leftbeyond the exposed side or surface of the disc-shaped portion 214 of theflywheel 202.

An antifriction bearing 206 is installed between an integralprotuberance of the flywheel 202 and the surface bounding an axialpassage at the center of the flywheel 203.

The difference between the main portion 13 of the flywheel 2 and themain portion 213 of the flywheel 202 is primarily that the axiallyextending toroidal portion 218 does not extend to both sides of thedisc-shaped portion 214 but only in a direction to the right so that theannular chamber 211 for the energy storing elements 210 of the damper209 is located radially outwardly of and directly surrounds the axiallyextending portion 223 of the cover 222. The latter forms part of thefriction clutch 204 which is provided on the flywheel 203. The axiallyextending portion 218 of the flywheel 202 cooperates with the componentor wall 219 to directly surround and to closely follow the outlines ofsubstantial portions (e.g., the radially outer halves) of the energystoring elements 210 in the radially outermost portion of the chamber211. The convolutions of the energy storing elements 210 bear againstand are guided by the internal surfaces of the portion 218 and wall 219when the flywheels 202 and 203 rotate about their common axis. Ifdesired or necessary, a suitable wear-resistant liner (see FIG. 1) canbe installed between the internal surfaces of the portion 218 and wall219 on the one hand and the adjacent portions of convolutions of theenergy storing elements 210 on the other hand. This prolongs the usefullife of the energy storing elements 210, of the portion 218 and/or ofthe wall 219.

FIG. 3 shows that the toroidal portion 218 of the flywheel 202 is inradial alignment with the second flywheel 203. This contributes to evenmore pronounced compactness of the torque transmitting apparatus 201,i.e., the first flywheel 202 can be said to completely surround andconfine the flywheel 203 so that only certain parts of the frictionclutch 204 project axially beyond the two flywheels.

FIG. 3 further shows that the axially extending toroidal portion 218 ofthe flywheel 202 and the toroidal wall 219 are virtual mirror images ofeach other, i.e., each of these parts surrounds approximately or exactlyone-half of the radially outermost portion of the annular chamber 211and half or nearly half of each energy storing element 210. The portion218 and the wall 219 are made of metallic sheet material and are weldedto each other, as at 220, in such a way that they seal the radiallyoutermost portion of the chamber 211 from the atmosphere. As alreadydescribed with reference to FIG. 1, the annular chamber 211 is dividedinto discrete compartments each of which confines one of the energystoring elements 210 and each of which is separated from the adjacentcompartment by a partition cooperating with one of the stressing arms221 to cause the elements 210 to store energy in response to angulardisplacement of at least one of the flywheels 202, 203 relative to theother fly:;heel. The partitions are formed as a result of depression ofpockets 218b in the external surface of the sheet metal portion 218 andas a result of formation of pockets 219b in the external surface of thewall 219. Each pocket 219b is located opposite a pocket 218b.

The axially extending (substantially cylindrical) portion 223 of thecover 222 is located radially inwardly of and is surrounded by thechamber 211. The cylindrical portion 223 surrounds the entire flywheel203 as well as the friction linings 229 of the clutch plate 205 and thepressure plate 228 of the friction clutch 204. The flywheel 203 isnon-rotatably connected to the cylindrical portion 223 of the cover 222by radially extending pins 224, sleeve-like fasteners or analogousparts. The illustrated pins 224 extend through registering radial boresor holes which are provided therefor in the cylindrical portion 223 andin the peripheral surface of the flywheel 203. It is equally possible toemploy threaded fasteners or to weld the cylindrical portion 223 to theflywheel 203.

The stressing arms 221 for the energy storing elements 210 in thecompartments of the chamber 211 are welded to the external surface 223aof the axially extending cylindrical portion 223 of the cover 222 andare spaced apart from the free end 223b of the cylindrical portion 223.The free end 223b is immediately or closely adjacent the inner side ofthe disc-shaped portion 214 of the flywheel 202. Each energy storingelement 210 can be stressed by one of the arms 221 and by thecorresponding partition between the respective pockets 218b, 219b. Inthe embodiment of FIG. 3, the arms 221 are separately produced partseach of which is individually welded or otherwise reliably secured toand extends from the external surface 223a of cylindrical portion 223 ofthe cover 222. Mounting of the arms 221 in such a way that they arespaced apart from the free end 223b of the cylindrical portion 223contributes to stability of the arms 221 because each of these arms issurrounded by circumferentially complete parts of the cylindricalportion 223 at the lefthand side as well as at the right-hand side.Otherwise stated, those parts of the cylindrical portion 223 which arewelded to the radially inner ends of the arms 221 are less likely toundergo deformation when the arms 221 engage and stress the adjacentenergy storing elements 210 than if the radially innermost portions ofthe arms 221 were welded or otherwise affixed to the free end 223b ofthe cylindrical portion 223.

FIG. 3 shows that the arms 221 are substantially or nearly coplanar withfriction linings 229 of the clutch plate 205.

An advantage of separately produced arms 221 which are subsequentlybonded or otherwise connected to the cylindrical portion 223 is that thearms 221 can be made of a material whose mechanical properties (such asresistance to wear and/or resistance to deformation) are superior to theproperties of the material of the cover 222. The wear upon the cover 222is a minute fraction of wear upon the arms 221 so that the quality ofthe apparatus 201 is not affected by making the cover 222 of a materialwhich is less resistant to wear than the material of the arms 221.

At least a portion of the chamber 211 is filled with a viscous fluid(such as oil or grease), and the fluid is confined in the chamber 211 bysealing means including a resilient sealing element 236. This sealingelement can include or constitute a membrane and includes an axiallyextending portion 236a which is a tight fit on the external surface ofthe free end 223b of cylindrical portion 223 of the cover 222. Aradially extending portion 236b of the resilient sealing element 236resembles a washer having an innermost portion which abuts the innerside of main portion 213 of the flywheel 202. The radially extendingportion 236b is installed in stressed condition so that it bears againstthe flywheel 202 in order to seal the radially inner portion of theannular chamber 211 from the clearance 230 between the two flywheels.

The apparatus 201 of FIG. 3 is ideally suited for use in motor vehicleswherein the means for transmitting torque between the engine and thevariable-speed transmission cannot occupy much space in the axialdirection of the flywheels. As can be seen in FIG. 3, the annularchamber 211 is located radially outwardly of the cylindrical portion 223of the cover 222 and immediately surrounds the flywheel 203 as well asthe friction linings 229 and a portion of the pressure plate 228, i.e.,the radially outermost portions of flywheel 229 and of a major part ofthe friction clutch 204 are surrounded by the chamber 211.

The means for cooling the flywheel 203 includes the clearance 230 whichcommunicates with openings or holes 234 in the disc-shaped portion 214of the flywheel- 202, with openings or holes 233 in the radially innerportion of the flywheel 203, and with openings 235 in the radiallyoutermost portion of the flywheel 223 inwardly adjacent the cylindricalportion 223 of the cover 222. Circulation of cooling air is enhanced byopenings or ports 238 in the region where the cylindrical portion 223merges into the radially extending portion of the cover 222. Theopenings 238 can constitute slots which are obtained by bending portionsof the material of the cover 222 radially outwardly and/or axiallyoutwardly so that the outwardly bent portions of the cover 222 act notunlike vanes or blades and enhance the cooling action of air upon theexterior of the cover 222. Moreover, the vanes or blades of the cover222 promote the circulation of air along the right-hand side of thepressure plate 228 and along the diaphragm spring 227. Air which issuesfrom the openings 234 exerts a cooling action between the engine and theexternal surface or outer side of disc-shaped portion 214 of theflywheel 202. The air stream or streams in the clearance 230 cool theleft-hand side of the flywheel 203. The air streams which issue from theports 238 can even produce a cooling action upon the variable-speedtransmission. The ports 238 can act as suction intakes which drawstreamlets of air from the interior of the friction clutch 204. Variousair streams which develop when the flywheels 202, 203 rotate areindicated in FIG. 3 by broken-line arrows.

A sealing element 231 is interposed between the frustoconical portion219a of the wall 219 and the external surface 223a of cylindricalportion 223 of the cover 222. The portion 219a extends in the axialdirection of the flywheels 202, 203 and its diameter decreases in adirection away from the chamber 211. The sealing element 231 has aV-shaped or C-shaped or U-shaped cross-sectional outline and its innerhalf can be shrunk or otherwise sealingly applied over the adjacentportion of the external surface 223a. The outer half of the sealingelement 231 is a hollow conical frustum which sealingly engages theinner side of the frustoconical portion 219a. It is often desirable tomount the sealing element 231 in such a way that its conical outer halfand the portion 219a define a diaphragm gland or a labyrinth seal sothat the element 231 need not actually touch the wall 219. This greatlyreduces the wear upon and prolongs the useful life of the sealingelement 231. Absence of friction between the sealing element 231 and thewall 219 is desirable and advantageous on the additional ground thatsuch friction could adversely influence the characteristic of the damper209, especially in the region of the zero position. However, it isequally within the purview of the invention to employ a sealing element31 at least the outer half of which is elastic and is installed instressed condition to bear upon the inner side of the frustoconicalportion 219a of the wall 219.

The utilization of a sealing element 231 which includes a frustoconicalouter half and cooperates with the inner side of the frustoconicalportion 219a of the wall 219 exhibits the advantage that any oil orgrease which happens to penetrate between the sealing element 231 andthe portion 219a tends to creep radially outwardly along the inner sideof the wall 219 under the action of centrifugal force, i.e., back intothe annular chamber 211.

The hub 205a of the clutch plate 205 has internal splines or teeth forengagement with complementary splines or teeth at the exterior of theinput shaft of the variable-speed transmission so that the hub 205a canmove axially of the input shaft but cannot rotate relative thereto. Theflange or carrier 205b of the clutch plate 205 is riveted or otherwisesecured to the hub 205a and carries the friction linings 229 which aredisposed between the friction surface 232 of the flywheel 203 and theadjacent surface of the pressure plate 228.

The cost of the torque transmitting apparatus 201 can be reducedconsiderably by resorting to a one-piece blank 270 of the type shown inFIG. 4. This blank can be produced by stamping or in any other suitableway and is thereupon severed at 271 and 271a to thus yield a cover 222,a wall 219 and a flange or friction lining carrier 205b. Thus, the sheetmaterial of the wall 219 is the same as that of the cover 222 and thatof the carrier or flange 205b. It is clear that the blank can bedesigned in such a way that it is to be severed at a single location (at271 or at 271a) in order to be divided into a wall 219 and a cover 222or into a cover 222 and a flange 205b. An advantage of the blank 270 isthat three parts of the torque transmitting apparatus 201 can beproduced simultaneously and with a very high degree of accuracy andreproducibility. Moreover, the percentage of waste is greatly reducedand can be reduced all the way to zero. All that is necessary is to makea ring-shaped cut at 271 and a ring-shaped cut at 271a.

FIG. 4 further shows that the blank portion which is to constitute thecover 222 can be provided with projections 273 which are to be convertedinto rivets (see FIG. 3) serving to hold an annular seat 227b for thediaphragm spring 227. The projections 272 are lugs which are provided onthe blank portion about to constitute the flange or carrier 205b. Thelugs 272 are used to secure sections 229a of friction linings 229 to thefinished flange 205b.

One of the leaf springs which serve to axially movably but non-rotatablycouple the pressure plate 228 to the cover 222 and to bias the pressureplate 228 axially and away from the friction linings 229 is shown inFIG. 3, as at 228a.

Pronounced compactness of the apparatus 201 (as seen in the axialdirection of the flywheels 202, 203) is attributable to the fact thedimensions of the clutch plate 205 and pressure plate 228 are selectedwith a view to ensure that these parts (together with the flywheel- 203)can be introduced into the space which is surrounded by the annularchamber 211. Thus, not only the friction surface 232 of the flywheel 203but also the friction surface of the pressure plate 228 is locatedradially inwardly of the radially innermost portions of energy storingelements 210 in the chamber 211. These features render it possible toencapsulate the secondary flywheel 203 and at least the major part ofthe friction clutch 204 in the space which is surrounded by the annularchamber 211. The primary flywheel 202 (this flywheel includes theportions 214, 218 and the wall 219 when the making of the welded joint220 is completed) can be said to constitute a shallow pan the radiallyoutermost portion of which receives the supply of viscous fluid and theenergy storing elements 210, and the remaining (central) part of whichreceives the secondary flywheel 203 and the major part of the frictionclutch 204.

The inner race of the bearing 206 can constitute an integral part of theflywheel 202 and/or the outer flange of this bearing can constitute anintegral part of the flywheel 203. The inner race can be an integralpart of the projection 250 so that the latter performs several functionsincluding centering the input element of the transmission and locatingthe rolling elements of the bearing.

The discrete stressing arms 221 can constitute simple flat stampings ofa material which can be readily welded to the axially extending portion223 of the cover 222. Since the arms 221 are spaced apart from the freeend 223b of the axially extending portion 223, the latter is less likelyto be deformed by the arms 221 when such arms are called upon to causethe adjacent elements 210 to store additional energy, or the cover 222can be made of thinner material because even such cover can properlywithstand deforming stresses which develop when at least one of theflywheels rotates relative to the other flywheel so that the arms 221cooperate with the partitions including the retainers of the primaryflywheel to stress the energy storing elements 210.

The blank 270 of FIG. 4 can be formed in a deep drawing, stamping,embossing or like machine.

It is often desirable to establish a discrete thermal barrier betweenthat flywheel which carries the antifriction bearing and the chamber forthe damper or dampers. FIG. 3 shows a thermal insulator or barrier 264which is installed between the peripheral surface of the flywheel 203and the cylindrical portion 223 of the cover 222. The thermal insulator264 can constitute a one-piece annular body which extends all the wayaround the flywheel 203. Alternatively, such thermal insulator can beassembled of two or more arcuate sections. In either event, theinsulator 264 is preferably located adjacent the openings 235. Theillustrated insulator 264 is assumed to be assembled of several arcuatesections one of which is shown in the lower part of FIG. 3. Theutilization of a composite thermal insulator is desirable andadvantageous because the sections of a composite insulator can bedistributed in such a way that they do not interfere with the flow of acoolant in the openings 235.

An important advantage of the thermal insulator 264 is that heat whichdevelops when the clutch 204 is actuated cannot be readily transmittedfrom the heated flywheel 203 to the cover 222 and thence (viacylindrical portion 223 and arms 221) to the supply of viscous fluid andto the energy storing elements 210 in the annular chamber 211. Thus, theinsulator 264 prevents thermal overstressing of the confined viscousfluid and/or of the energy storing elements 10. The provision of suchthermal insulator constitutes a contribution which is believed to beworthy of patent protection with or independently of other novelfeatures of the improved torque transmitting apparatus. Similar oridentical thermal insulators or barriers can be installed in each of thedescribed and shown torque transmitting apparatus. For example, athermal barrier or insulator can be installed in the apparatus 101 ofFIG. 2 between the radially outermost portion 161 of the membrane 160and the radially outermost portion 159 of the cover 122 and/or theradially outermost portion 156a of the ring 156. Each torquetransmitting apparatus can be provided with two or more thermalinsulators.

The thermal insulator or insulators can be made of a highlyheat-resistant plastic material such as, for example, polyamidide orpolyether ether ketone (PEEK).

The illustrated thermal insulator 264 is particularly effective in theregion between the hot secondary flywheel 203 and the arms 221 whichcontact the supply of viscous liquid and the energy storing elements210, i.e., this thermal insulator is effective to prevent overheating ofthe arms 221 and hence an overheating of the viscous liquid and/or ofthe energy storing elements 210. This contributes to longer useful lifeof the damper 209 and of the entire torque transmitting apparatus 201.The thermal insulator 264 also serves as a means for shielding theclutch cover 222 from overheating because it is installed between theperipheral surface of the secondary flywheel 203 and the cylindricalportion 223 of the cover 222.

FIG. 5 shows a torque transmitting apparatus 301. All such parts of thisapparatus which are identical with or clearly analogous to correspondingparts of the apparatus 1 of FIG. 1 are denoted by similar referencecharacters plus 300. The apparatus 301 constitutes a modification of theapparatus 201 of FIG. 3 and differs from the apparatus 201 in that theannular chamber 311 accommodates two dampers respectively havingcircumferentially extending arcuate energy storing elements 310, 310a inthe form of coil springs. The friction clutch 304 comprises a cover 322having an axially extending cylindrical portion 323 which surrounds theflywheel 303, the friction linings 329 of the clutch plate 305, thepressure plate 328 and the diaphragm spring 327. The main portion 313 ofthe primary flywheel 302 includes the disc-shaped portion 314 and theaxially extending portion 318 which cooperates with the wall orcomponent 319 to define the annular chamber 311. The energy storingelements 310 alternate with stressing portions or arms 321 which arewelded or otherwise reliably secured to the external surface of thecylindrical portion 323 in a manner similar to that described withreference to the stressing arms 221 of FIG. 3. The energy storingelements 310a alternate with stressing portions or arms 321a which arealso secured to the external surface of the cylindrical portion 323. Thearms 321 cooperate with partitions which are formed as a result ofprovision of pockets 318b in the external surface of the axiallyextending portion 318, and the arms 321a cooperate with partitions whichare formed as a result of the provision of pockets 319b in the externalsurface of the wall 319. Each pocket 318b is located opposite a retainer318c which forms part of a ring 320a welded to the abutting ends of theaxially extending portion 318 and wall 319. The ring 320a furthercarries retainers 319c each of which is located opposite a pocket 319b.The pockets 318b and the retainers 318c are staggered relative to thepockets 319b and the retainers 319c in the circumferential direction ofthe flywheels 302 and 303. The retainers 218c, 219c are disposed betweenthe two sets of stressing arms 321, 321a (as seen in the axial directionof the flywheels 302, 303).

The ring 320a can be omitted if the retainers 318c, 319c are weldeddirectly to the flywheel 302, namely to the axially extending portion318 and to the wall 319, respectively. The portion 318 and the wall 319can be considered to constitute integral parts of the flywheel 302. Theretainers 318c can constitute integral parts of the axially extendingportion 318, and the retainers 319c can constitute integral parts of thewall 319. Irrespective of the manner of forming and securing theretainers 318c, 319c to the flywheel 302, they are provided at theinternal surface of that part (318, 319) of the flywheel- 302 which isradially outwardly adjacent the annular chamber 311.

The distribution of retainers 318c and pockets 318b on the one hand, andof the retainers 319c and pockets 319b on the other hand (as seen in thecircumferential direction of the cylindrical portion 323), is preferablysuch that each retainer 318c and the corresponding pocket 318c arelocated substantially midway between the ends of an energy storingelement 310a, and that each retainer 319c and the corresponding pocket391b are located substantially midway between the ends of an energystoring element 310. In other words, the compartments for the elements310 are staggered relative to the compartments for the elements 310a inthe circumferential direction of the cylindrical portion 323. Eachenergy storing element 310 is located between a stressing arm 321 (whichcan turn with the flywheel 303) and a composite partition including oneof the retainers 318c and the corresponding depression in the axiallyextending portion 318 adjacent the respective pocket 318b. Analogously,each energy storing element 310 is confined between an arm 319a and aretainer 319c which, in turn, is aligned with the depressed portion ofthe wall 319a adjacent the respective pocket 319b. Each of the arms 321is located in or close to a plane including the axes of the energystoring elements 310, and each arm 321a is located in or close to aplane including the axes of the energy storing elements 310a. Thepockets 318b and the retainers 318c are located at opposite sides of theplane of the arms 321, and the pockets 319b and the retainers 319c arelocated at opposite sides of the plane of the arms 321a. Suchdistribution of the pockets 318b, 319b, retainers 318c, 319c and arms321, 321a ensures highly predictable and optimal stressing of the energystoring elements 310, 310a in response to angular displacement of atleast one of the flywheels 302, 303 relative to the other flywheel.

As mentioned above, the ring 320a is optional because the retainers 318ccan constitute integral parts of the axially extending portion 318 andthe retainers 319c can constitute integral parts of the wall 319.

The energy storing elements 310 operate in parallel with the energystoring elements 310a. However, it is within the purview of theinvention to assemble a composite damper, including two sets of energystoring elements, in such a way that the energy storing elements 310operate in series with the energy storing elements 310a.

The secondary flywheel 303 is mounted on the outer race 317 of anantifriction ball bearing 306 which has an inner race 316 traversed byholes for the shanks of screws 308. The flywheel 303 has an axialpassage 303a for the outer race 317. In order to ensure that theflywheel 303 will not be caused to move axially in response todisengagement of the friction clutch 304, the flywheel 303 comprises aradially inwardly extending collar 303b which is located at theright-hand end of the passage 303a for the outer race 317. The latterabuts the adjacent shoulder of the collar 303b. The flywheel 303 can beshrunk onto the outer race 317 of the bearing 306, or the outer race 317can be a press fit in the passage 303a.

It is further possible to secure the outer race 317 and the flywheel 303against axial movement relative to each other by providing the surfacesurrounding the passage 303a with a groove for a split ring 303c whichalso extends into a groove in the external surface of the outer race317.

The inner race 316 of the bearing 306 surrounds a short annularprotuberance 315 of the flywheel 302 and such inner race can be said toserve as a washer for the heads of the screws 308. When the screws 308are driven home into the tapped bores of the output element of anengine, their heads bias the inner race 316 against the inner side ofthe disc-shaped portion 314 to ensure that the bearing 306 is maintainedin a predetermined axial position, namely immediately adjacent the innerside of the disc-shaped portion 314. The inner race 316 has bores orholes 307a which are in register with the holes 307 in the disc-shapedportion 314. The diameters of the holes 307 can match the diameters ofthe holes 307a. The protuberance 315 serves as a means for centering thebearing 306 in the flywheel 302, and the outer race 317 centers theflywheel 303 on the flywheel 302. As shown in FIG. 5, the axial lengthof the protuberance 315 can be less than the axial length of the innerrace 316. The inner race 316 can be a press fit on the protuberance 315,and the flywheel 303 can be mounted directly on the outer race 317. Inorder to avoid overheating of the bearing 306, the apparatus 301 of FIG.5 can be provided with a thermal insulator (e.g., a cylindrical insertof suitable plastic material) which is interposed between the flywheel303 and the outer race 317 of the bearing 306.

FIGS. 6 and 7 show a modification of the apparatus 201 or 301. Thesecondary flywheel 403 is surrounded by the axially extendingcylindrical portion 423 of the cover 422. The flywheel 403 is welded (at424) to the cylindrical portion 423 by way of one or more projections orinserts 474 made of steel or another material which can be readilybonded to the material of the cylindrical portion 423. The illustratedinsert 474 comprises a centrally located lobe 474a which extendsradially inwardly and is bounded by a convex surface abutting acomplementary concave surface in a recess 475 provided in the peripheryof the flywheel 403. Thus, the lobe 474a prevents angular movements ofthe insert 474 and the flywheel 403 relative to each other. The insert474 further comprises two extensions 474b, 474c at the ends of the lobe474a. These extensions are received in a groove 476 of the flywheel 403so that the latter cannot move axially relative to the insert 474 and/orvice versa. As a rule, the flywheel 403 is a metallic casting.

The peripheral surface of the flywheel 403 is normally provided withseveral equidistant recesses 475 each of which receives the lobe 474a ofa discrete insert 474. The recesses 475 are provided at one side face ofthe flywheel 403 and they communicate with the circumferentiallyextending groove 476 which is machined into or is otherwise formed inthe peripheral surface of the flywheel 403 to receive the extensions474b, 474c of all inserts 474. Once an insert 474 is properly installedin the respective recess 475 and in the adjacent portion of the groove476, and the flywheel 403 is inserted into the cylindrical portion 423of the cover 422, the insert is reliably held against axial and/orradial movement relative to the flywheel 403.

FIG. 6 shows that the welded joint 424 which bonds the illustratedinsert 474 to the flywheel 403 is located between the free end 423b ofthe cylindrical portion 423 and the plane for the stressing arms 421which alternate with the energy storing elements (not shown) of thedamper acting between the flywheels 402 and 403.

In order to connect the flywheel 403 to the cover 422, the inserts 474are properly installed in the flywheel 403 in the aforedescribed manner,i.e., the lobes 474a abut the concave surfaces in the respectiverecesses 475 and the extensions 474b, 474c are received in the groove476. The next step involves placing the clutch plate 405 next to thefriction generating surface 432 of the flywheel 403, the latter is thenintroduced into the cylindrical portion 423 of the cover 422, and thecylindrical portion 423 is ready to be welded (as at 424) to the inserts474, i.e., to the flywheel 403.

FIG. 8 shows that the secondary flywheel 503 can be welded (at 524) tothe cylindrical portion 523 of the cover 522 in a different way. Theperipheral surface of the flywheel 503 is formed with radially extendingblind bores or holes 575 each of which receives a pin-shaped orrivet-shaped projection or insert 574 consisting of a material which canbe readily welded to the cylindrical portion 523. For example, theinserts 574 can be made of steel, the same as the cover 522. The inserts574 can be deformed upon insertion into the respective bores or holes575 so that they at least substantially fill the respective bores orholes 575 and their external surfaces are in full contact with thesurfaces bounding the bores 575. This prevents stray movements of theflywheel 503 relative to the cylindrical portion 523. The axial positionof the welded joint 524 relative to the free end 523b of the cylindricalportion 523 and the adjacent stressing arm 521 is the same as describedfor the joint 424 of FIG. 6.

The character 502 denotes a portion of the primary flywheel which isclosely or immediately adjacent the flywheel 523 and defines with thelatter a radially extending annular clearance corresponding to theclearance 30 in the apparatus 1 of FIG. 1.

The stressing arms 421, 521 are preferably staggered or offset relativeto the welded joints 424, 524 in the circumferential direction of therespective flywheels 403, 503. Such staggering of the stressing arms isdesirable and advantageous because the stressing arms are not in the wayduring making of the welded joints 424, 524.

The apparatus for forming the welded joints 424, 524 from the externalsurfaces of the cylindrical portions 423, 523 are well known in the art.Such apparatus can constitute spot welding machines, laser welders orcapacitive (stored energy) welding machines.

FIG. 9 shows a portion of a torque transmitting apparatus wherein thecylindrical portion 623 of the cover 622 of the friction clutch isintegral with stressing arms 621 and the cylindrical portion 623 iswelded to the radially outermost portion of a washer-like insert 674.The insert 674 extends into a recess 675 at the front side of thesecondary flywheel 603 and is reliably secured to this flywheel byrivets 624a. The welded joint between the cylindrical portion 623 andthe insert 674 is shown at 624. The orientation of the arms 621 can bethe same as that of the arms 21 in the apparatus 1 of FIG. 1. The rivets624a are preferably designed and mounted in such a way that they holdthe insert 674 against any (axial and/or radial) movement relative tothe flywheel 603. The latter is immediately or closely adjacent theprimary flywheel 602.

FIGS. 10 to 12 illustrate a further mode of non-rotatably connecting thesecondary flywheel 703 with the cylindrical portion 723 of the cover722. The cylindrical portion 723 can constitute one of severalcylindrical portions of the cover 722, and the illustrated portion 723has sections 723d extending axially of the apparatus and transversely aswell as circumferentially of the peripheral surface of the flywheel 703.The sections 723d have projections 724 in the form of lobes or warts.Such projections extend into complementary recesses or sockets 774 inthe peripheral surface of the flywheel 703. The recesses 774 have acruciform shape (FIG. 12). To this end, the peripheral surface of theflywheel 703 is provided with a circumferentially extending groove 775(having a square or rectangular cross-sectional outline) and withaxially parallel grooves 776 which cross the groove 775 to thus definethe respective recesses 774. The axially extending grooves 776 arebounded by concave surfaces of the flywheel 703, and each such surfacepreferably extends along an arc of at least close to 180°. The grooves776 cross the circumferentially extending groove 775 at an angle of orclose to 90°. The depth of the grooves 776 can equal or approximate thedepth of the groove 775. It is presently preferred to select thedimensions of the axially parallel grooves 776 in a manner as shown inFIG. 11, i.e., the deepmost portions of the grooves 776 are locatedslightly radially outwardly of the bottom surface in the groove 775.

An advantage of the cruciform recesses 774 is that the material of thecylindrical portion 723 can flow into such recesses during formation ofthe lobes 724, i.e., during application of deforming force by a tool 777which is shown in FIG. 10 and has a cylindrical or polygonal working end777a. The working end 777a penetrates into the external surface of thecylindrical portion 723 outwardly adjacent an intersection of the groove775 with a groove 776 to thus form a lobe 724 which penetrates into theadjacent portions of the circumferentially extending groove 775 as wellas into portions of the respective axially parallel groove 776 at bothsides of the groove 775. This ensures the establishment of a connectionwhich ensures that the cover 722 and the flywheel 703 cannot moverelative to each other in the axial and/or circumferential direction ofthe secondary flywheel.

The feature that the displaced material of the cylindrical portion 723can flow into the groove 775 simultaneously with flow of such materialinto the respective groove 776 ensures that the grooves 775, 776 canreceive greater or smaller quantities of material of the cover 223. Thisgreatly reduces the likelihood of cracking or chipping of the flywheel703 (which is normally a casting) in the region of a recess 774. Thereason is that the displaced material of the cylindrical portion 723 hasroom to flow into the groove 775 and into both halves of the respectivegroove 776 irrespective of whether the working end 777a of the tool 777displaces a larger or a smaller quantity of material of the cylindricalportion 723. Thus, the flywheel 703 is not unduly stressed in theregions of its recesses 774 because such recesses are designed toreceive larger or smaller quantities of ductile material of thecylindrical portion 723, i.e., each recess can receive a larger orsmaller lobe 724 without affecting the integrity of the flywheel 703and/or the reliability of connection between such flywheel and thecylindrical portion 723. The deforming action of the tool 777 ispreferably such that the material of the cylindrical portion 723 iscaused to flow into the recesses 774. The working end 777a of theillustrated tool 777 is a relatively short cylinder. The mechanism ormachine which is used to force the working end 777a of the tool 777 intothe external surface of the cylindrical portion 723 is not shown becauseit forms no part of the present invention.

The making of connections by way of recesses 774 and lobes 724 is asfollows:

The flywheel 703 is introduced into the cylindrical portion 723 of thecover 722 to an extent which is necessary to ensure adequate stressingof the diaphragm spring forming part of the friction clutch includingthe cover 722 (note the diaphragm spring 27 in the apparatus 1 of FIG.1). Stressing of the diaphragm spring should suffice to ensurepredictable engagement and disengagement of the friction clutch whichincludes the cover 222 for the entire contemplated useful life of thetorque transmitting apparatus. The tool 777 is put to use once thediaphragm spring is properly stressed, and the cylindrical portion 723is thus provided with lobes 724 which penetrate into the adjacentportions of the grooves 775, 776 to impart to the lobes a cruciformshape which is ideally suited to ensure the establishment of a highlyreliable connection against movements of the cylindrical portion 723 inthe axial and circumferential directions of the flywheel 703.

The torque transmitting apparatus which embodies the structure of FIGS.10 to 12 need not be provided with a shoulder corresponding to theshoulder 25 in the apparatus 1 of FIG. 1, i.e., it is not necessary toprovide a means (other than the lobes 724) for ensuring that the axialand angular positions of the flywheel 703 relative to the cover 722 willremain unchanged during the entire useful life of the apparatus.

Another advantage of the apparatus which embodies the structure of FIGS.10 to 12 is that it can compensate for any and all tolerances whichinfluence the stressing of the diaphragm spring in the friction clutchof a fully assembled torque transmitting apparatus. Thus, the flywheel703 is simply forced into the cylindrical portion 723 and toward thepressure plate and diaphragm spring of the friction clutch until thediaphragm spring of the friction clutch stores a requisite accuratelydetermined amount of energy such as is needed for predictable engagementand disengagement of the friction clutch. The mode of operation of afriction clutch wherein the diaphragm spring is stressed in a manner asdescribed with reference to FIGS. 10 to 12 is more predictable andvaries little or not at all for long periods of time.

The connection which employs the cruciform or X-shaped or a similarsocket 774 and the projection 724 can be used with advantage to preventany movements of the clutch cover 722 and the secondary flywheel 703relative to each other, but such connection is equally useful in manyother types of apparatus or machines where two or more parts must besecured to each other in such a way that they are held against relativemovement in a plurality of different directions. In other words, theutility of the connection which is shown in FIGS. 10-12 is not limitedto utilization in an apparatus which is to be installed in the powertrain between the engine and the wheels or other ground-contactingelements of a vehicle.

The grooves 776 need not extend at right angles to the groove 775, i.e.,the grooves 776 need not be exactly parallel to the axis of thesecondary flywheel 703. All that counts is to provide the flywheel 703with cruciform, X-shaped or similar or analogous sockets which provideroom for more material than is absolutely necessary to establish areliable connection against relative movements of the flywheel 703 andcover 722 in the axial and/or circumferential direction of the flywheel.

It is further clear that the grooves 776 need not be bounded bysemicylindrical or other concave surfaces. Such surfaces are easier toform because the material of the flywheel 703 can be removed by arotating drill or by an analogous material removing tool.

An advantage of a deforming technique which causes the material of thecover 722 to actually flow into the sockets 774 is that this ensureshighly predictable filling of each socket 774, at least at or close tothe intersection of the groove 775 with the respective axially parallelgroove 776. Thus, a reliable connection is established as soon as atleast some material of the cover 722 flows beyond the intersectionproper so that it enters the channel 775 as well as the respectivechannel 776.

The illustrated tool 777 can be replaced with a tool having asemispherical, conical or polygonal working end without departing fromthe spirit of the invention.

FIG. 13 shows a sealing element 831 which can be utilized with advantagein the torque transmitting apparatus of FIG. 3 or in any other apparatuswherein a reliable seal must be established between a stationary partand a rotary part or between two rotary parts one of which rotates at adifferent speed and/or in a different direction. The sealing element 831comprises a ring-shaped section or support 831a and a washer-likesection 831b which is or can be installed in stressed condition notunlike a diaphragm spring. This composite sealing element 831 isinstalled between the frustoconical end portion 819a of the wall 819 andthe external surface of cylindrical portion 823 of the cover 822. Thewall 819 shares all angular movements of the primary flywheel (not shownin FIG. 13), and the cover 822 shares all angular movements of thesecondary flywheel (which is assumed to be non-rotatably connected withthe cylindrical portion 823). The axially extending leg 828 of thesection 831a is adjacent the external surface 823a of the cylindricalsection 823. The section 831a has a substantially L-shapedcross-sectional outline and its other leg 829 extends substantiallyradially of the cylindrical portion 823 but is preferably a conicalfrustum with a relatively large acute angle between the legs 828 and829. Thus, the conicity of the right-hand side of the leg 829 need notbe very pronounced. The leg 829 tapers in a direction radially outwardlyof the external surface 823a and slightly toward the annular chamber(not shown) which is located to the left of FIG. 13 and is partiallysurrounded by the wall 819.

That surface of the end portion 819a which is adjacent the section 831bis a conical frustum which tapers in the same way as the leg 829 but notnecessarily to the same extent. The section 831b between the leg 829 andthe end portion 819a stores energy; the radially innermost part of thesection 831b reacts against the junction of the legs 828, 829 and theradially outermost part of the section 831b bears against thefrustoconical surface of the end portion 819a. The section 831a can be aforce fit on the external surface 823a of the cylindrical portion 823;the external surface 823a is then finished with at least some degree ofprecision, e.g., in a grinding or polishing machine. Alternatively, acertain part of the cylindrical portion 823 (namely the part which is tobe surrounded by the leg 828) is treated and calibrated in a stamping,upsetting, extruding or other suitable machine.

In order to assemble the sealing element 831 of FIG. 13, the sections831a, 831b are mounted on the cylindrical portion 823 of the cover 822before the wall 819 is welded to the primary flywheel (note the weldedjoint 20 in FIG. 1) and the sections 831a, 831b assume axial positionsbeyond the final axial positions, i.e., further away from the primaryflywheel. The next step involves positioning of the wall 819 adjacentthe section 831b as shown in FIG. 13 and moving the wall 819 to the leftso that it ultimately abuts the radially outermost portion (see theportion 18 in FIG. 1) of the primary flywheel. The primary flywheel andthe wall 819 are then welded to each other (note the welded joint 20 ofFIG. 1). As the wall 819 moves to the left, the end portion 819astresses the section 831b so that the conicity of the section 831b isthe same as that of the lefthand side of the end portion 819a, and anyfurther leftward movement of the wall 819 entails a shifting of thesection 831a along the external surface 823a of the cylindrical portion823. The leftward movement of the wall 819 and of the sections 831a,831b is terminated when the wall 819 reaches a proper axial position forwelding to the adjacent portion [such as 18) of the primary flywheel.The zone in which the section 831b bears upon the end portion 819a andthe magnitude of force which is to urge the section 831b against the endportion 819a are selected in such a way that the wall 819 undergoes acertain amount of elastic deformation not later than when it reaches theadjacent portion (18) of the primary flywheel. This ensures that thestressed wall 819 can dissipate some stored energy when the weldingoperation (at 20) is completed. Such dissipation of energy entails somerightward movement of the end portion 819a so that the section 831b canassume the angular position which is shown in FIG. 13. This suffices toensure the establishment of a reliable sealing action between the endportion 819a on the one hand and the section 831a of the sealing element831 on the other hand.

The improved apparatus is susceptible o many additional modificationswithout departing from the spirit of the invention. For example, thefeatures of the apparatus 1 can be combined with those of the apparatusof FIGS. 2-13, the features of the apparatus 101 can be combined withthose of the apparatus of FIGS. 1 and 3-13, and so forth.

Furthermore, the illustrated bearings between the primary and secondaryflywheels can be replaced with a bearing which surrounds the holes forthe screws that are used to secure the torque transmitting apparatus tothe rotary output element of an engine. For example, the apparatus 301of FIG. 5 can be modified in such a way that the entire bearing 306 islocated radially outwardly of the set of holes 307 in the disc-shapedportion 314 of the primary flywheel 302.

The sealing means for the annular chamber which confines one or moredampers can be designed in such a way that at least one of its partsoperates directly between the radially outermost portion of thesecondary flywheel and a member which rotates with the primary flywheel.Thus, the secondary flywheel- can bound a portion of the annularchamber.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of theaforedescribed contribution to the art and, therefore, such adaptationsshould and are intended to be comprehended within the meaning and rangeof equivalence of the appended claims.

What is claimed is:
 1. A torque transmitting apparatus for use in motorvehicles, comprising a first rotary flywheel connectable with an engineof a vehicle; a second rotary flywheel connectable with a transmissionof the vehicle by a friction clutch; at least one antifriction bearingbetween said flywheels; and at least one damper operative to opposerotation of said flywheels relative to each other and disposed in anannular chamber defined at least in part by said first flywheel, saiddamper including energy storing elements acting in the circumferentialdirection of said flywheels and said clutch including a cover affixed tosaid second flywheel and having an outer portion provided with stressingportions extending into said chamber and engaging said energy storingelements.
 2. The apparatus of claim 1, wherein said stressing portionsare integral with said cover.
 3. The apparatus of claim 1, furthercomprising a supply of viscous fluid at least partially filling saidchamber, and means for at least substantially sealing said chamber fromthe atmosphere, said cover having an outer side and said sealing meanscomprising a sealing element which is interposed between said outer sideand a component which defines a portion of said chamber.
 4. Theapparatus of claim 3, wherein said sealing element is mounted on saidcomponent.
 5. The apparatus of claim 3, wherein said sealing element ismounted on said cover.
 6. The apparatus of claim 1, wherein said secondflywheel has a peripheral surface and further comprising means forconnecting said cover with said second flywheel at said peripheralsurface.
 7. The apparatus of claim 1, further comprising at least onestressing member affixed to said cover and including said stressingportions.
 8. The apparatus of claim 7, wherein said cover has an outermarginal portion and said at least one stressing member is affixed tosaid outer marginal portion.
 9. The apparatus of claim 1, furthercomprising means for affixing said cover to said second flywheel, saidaffixing means comprising a membrane.
 10. The apparatus of claim 9,wherein said cover has an outer marginal portion which is secured tosaid membrane, said membrane surrounding said second flywheel.
 11. Theapparatus of claim 9, further comprising at least one securing memberincluding said stressing portions, said cover having an outer marginalportion and said membrane including a portion which is clamped betweensaid at least one securing member and said marginal portion.
 12. Theapparatus of claim 9, wherein said second flywheel has a sideconfronting said first flywheel and facing away from said frictionclutch, said membrane having a portion extending radially of said firstflywheel and along said side of said second flywheel.
 13. The apparatusof claim 12, wherein said side of said second flywheel has at least oneventilating channel which is overlapped by said portion of saidmembrane, said at least one channel having an inlet portion and anoutlet portion, one of said inlet and outlet portions being nearer toand the other of said inlet and outlet portions being more distant fromsaid at least one bearing.
 14. The apparatus of claim 9, wherein saidmembrane includes a portion which centers said friction clutch relativeto said second flywheel.
 15. The apparatus of claim 1, wherein saidchamber is at least substantially sealed from the atmosphere and saidflywheels include portions which are immediately adjacent each otherradially inwardly of said chamber and define a clearance.
 16. Theapparatus of claim 1, wherein said second flywheel has a frictionsurface for a clutch plate of said friction clutch, said at least onebearing being disposed radially inwardly of said friction surface and atleast a portion of said friction surface being disposed in a plane whichis normal to the axes of said flywheels and is at least adjacent said atleast one bearing.
 17. The apparatus of claim 1, wherein said flywheelshave neighboring portions which define an annular ventilating clearancefor the passage of a cooling air stream.
 18. The apparatus of claim 1,wherein said flywheels include portions which are closely adjacent eachother and define a narrow clearance, said portion of said first flywheelhaving at least one opening which communicates with said clearance. 19.Apparatus according to claim 1, wherein said flywheels include portionswhich are adjacent each other and define a narrow clearance, said secondflywheel having a friction surface adjacent a clutch plate of saidfriction clutch and said portion of said second flywheel having at leastone opening communicating with said clearance radially outwardly of saidfriction surface.
 20. The apparatus of claim 1, further comprising meansfor fastening said first flywheel to a rotary output element of theengine, said fastening means being located radially inwardly of said atleast one bearing.
 21. The apparatus of claim 1, further comprisingmeans for fastening said first flywheel to a rotary output element ofthe engine, said fastening means comprising a plurality of rotaryfasteners located radially outwardly of said at least one bearing. 22.The apparatus of claim 21, wherein said second flywheel has axiallyextending openings positioned to permit engagement of said fasteners bya rotating tool.
 23. The apparatus of claim 1, wherein one of saidflywheels is provided with a protuberance and said at least one bearingincludes a first race surrounding said protuberance, said at least onebearing further including a second race which supports the other of saidflywheels, said first flywheel having holes for fasteners which securesaid first flywheel to a rotary output element of the engine and saidholes being located radially outwardly of said races.
 24. The apparatusof claim 23, wherein said protuberance is integral with said oneflywheel.
 25. The apparatus of claim 23, wherein said protuberance isprovided on said first flywheel.
 26. The apparatus of claim 1, whereinat least one of said flywheels defines an axial passage and saidfriction clutch further comprises a clutch plate having a hub in saidpassage.
 27. The apparatus of claim 1, wherein one of said flywheels hasan annular protuberance and said at least one bearing includes a racewhich is of one piece with said protuberance.
 28. The apparatus of claim1, wherein said first flywheel is provided with a protuberance and saidat least one bearing has an inner race and an outer race, said outerrace being of one piece with said protuberance.
 29. The apparatus ofclaim 1, wherein said friction clutch further comprises a clutch plate,said flywheels and said friction clutch together constituting apreassembled unit which is connectable to a rotary output element of theengine.
 30. The apparatus of claim 29, wherein said preassembled unitfurther comprises said at least one bearing.
 31. The apparatus of claim29, wherein said friction clutch further comprises a pressure platebetween said clutch plate and said second flywheel, said clutch platebeing centered in said unit between said second flywheel and saidpressure plate.
 32. The apparatus of claim 29, wherein said firstflywheel has first holes and further comprising means for fastening saidfirst flywheel to a rotary output element of the engine, said fasteningmeans including fasteners in said first holes and said clutch platehaving second holes, said friction clutch further including a pressureplate and said clutch plate being centered between said clutch plate andsaid second flywheel so that each second hole is in at least partialalignment with one of said first holes.
 33. The apparatus of claim 1,further comprising a pilot bearing in said first flywheel.
 34. Theapparatus of claim 1, further comprising means for separably couplingsaid friction clutch to said second flywheel, said flywheels and saidclutch together constituting a preassembled unit which is connectable toa rotary output element of the engine.
 35. The apparatus of claim 1,wherein said cover includes an axially extending radially outer portionadjacent said chamber.
 36. The apparatus of claim 1, wherein saidchamber is disposed radially outwardly of said cover.
 37. The apparatusof claim 1, wherein said stressing portions include discrete lugs whichare affixed to said cover.
 38. The apparatus of claim 1, wherein saidcover includes an axially extending radially outer portion having a freeend adjacent said first flywheel, said stressing portions being providedat the exterior of said axially extending portion and being spaced apartfrom said free end.
 39. The apparatus of claim 1, further comprising awall bounding a portion of said chamber and surrounding portions of saidenergy storing elements, said wall and said cover consisting of the samematerial.
 40. The apparatus of claim 1, further comprising a wallbounding a portion of said chamber and surrounding portions of saidenergy storing elements, said friction clutch further comprising aclutch plate having a hub and a carrier of friction linings surroundingsaid hub, said carrier consisting of a material which is the same as thematerial of one of the parts including said cover and said wall.
 41. Theapparatus of claim 40, wherein said cover, said carrier and said wallconstitute separated sections of an originally one-piece blank.
 42. Theapparatus of claim 1, further comprising a welded connection betweensaid cover and said second flywheel.
 43. The apparatus of claim 1,further comprising a thermal insulator between said second flywheel andsaid chamber.
 44. The apparatus of claim 1, further comprising a thermalinsulator between said second flywheel and said stressing portions. 45.The apparatus of claim 1, wherein said cover includes a substantiallyaxially extending portion which surrounds said second flywheel, saidaxially extending portion having at least one projection extending intoa radial recess of said second flywheel.
 46. The apparatus of claim 1,wherein said clutch further comprises a pressure plate connected withand movable axially of said cover, a clutch plate between said secondflywheel and said pressure plate, and at least one spring reactingagainst said cover and bearing against said pressure plate to urge thepressure plate against said clutch plate, said cover having an axiallyextending portion which surrounds said second flywheel and said secondflywheel having a peripheral surface provided with at least onesubstantially cruciform recess, said axially extending portion having aprojection substantially complementary to and extending into said atleast one recess.
 47. The apparatus of claim 46, wherein said peripheralsurface has a circumferentially extending groove forming part of said atleast one recess.
 48. The apparatus of claim 46, wherein said peripheralsurface has at least one substantially axially parallel groove formingpart of said at least one recess.
 49. The apparatus of claim 48, whereinsaid peripheral surface has at least one circumferentially extendinggroove forming part of said at least one recess and intersecting said atleast one substantially axially parallel groove at an angle at leastclose to 90°.
 50. The apparatus of claim 48, wherein said secondflywheel has a concave surface bounding said at least one groove. 51.The apparatus of claim 46, wherein said projection is an integralstamped part of said axially extending portion.
 52. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle; a second rotaryflywheel connectable with a transmission by a friction clutch having acover connected to said second flywheel- at least one damper operativeto oppose rotation of said flywheels relative to each other and disposedat least in part in an annular chamber defined in part by said firstflywheel; a component defining another part of said chamber; a supply ofviscous fluid at least partially filling said chamber; and means for atleast substantially sealing said chamber from the atmosphere, said coverhaving an external surface and said sealing means including a sealingelement interposed between the external surface of said cover and saidcomponent.
 53. The apparatus of claim 48, wherein said flywheels includeneighboring portions extending radially inwardly from said toroidalportion and defining a clearance.
 54. A torque transmitting apparatusfor use in motor vehicles, comprising a first rotary flywheelconnectable with an engine of a vehicle; a second rotary flywheelconnectable with a transmission of the vehicle by a friction clutchhaving a cover; and at least one damper operative to oppose rotation ofsaid flywheels relative to each other and disposed in an annular chamberwhich is defined at least in part by one of said flywheels and isdisposed radially outwardly of said cover.
 55. A torque transmittingapparatus for use in motor vehicles, comprising a first rotary flywheelconnectable with an engine of a vehicle; a second rotary flywheelconnectable with a transmission of the vehicle by a friction clutch; atleast one damper operative to oppose rotation of said flywheels relativeto each other and disposed in an annular chamber defined at least inpart by one of said flywheels; and at least one thermal barrier betweensaid second flywheel and said chamber.
 56. A torque transmittingapparatus for use in motor vehicles, comprising a first rotary flywheelconnectable with an engine of a vehicle; a second rotary flywheelconnectable with a transmission of the vehicle; at least one damperoperative to oppose rotation of said flywheels relative to each otherand including a plurality of energy storing elements on said firstflywheel; stressing portions rotatable with said second flywheel andengaging said energy storing elements; and at least one thermal barrierinterposed between said second flywheel and said stressing portions. 57.A torque transmitting apparatus for use in motor vehicles, comprising afirst rotary flywheel connectable with an engine of a vehicle; a secondrotary flywheel connectable with a transmission of the vehicle by afriction clutch having a cover with an axially extending portionsurrounding said second flywheel, a pressure plate axially movablyconnected with said cover, a clutch plate between said second flywheeland said pressure plate and at least one spring reacting against saidcover and bearing against said pressure plate to urge the clutch plateagainst said second flywheel, said second flywheel having a peripheralsurface within said axially extending portion; means for connecting saidsecond flywheel to said cover including at least one substantiallycruciform recess in said peripheral surface and a projection provided onsaid axially extending portion and extending into said recess; and atleast one damper operative to oppose rotation of said flywheels relativeto each other.
 58. A torque transmitting apparatus comprising a firstrotary flywheel connectable with an engine; a second rotary flywheelconnectable with and disconnectable from a transmission by a frictionclutch; an antifriction bearing between said flywheels; and at least onedamper operative to oppose rotation of said flywheels relative to eachother and disposed in an annular chamber defined at least in part bysaid first flywheel, said damper including energy storing elementsacting in the circumferential direction of said flywheels and saidclutch including a cover connected with said second flywheel, said atleast one damper further comprising stressing portions which engage saidenergy storing elements to transmit to the second flywheel only aportion of torque which is transmittable by the apparatus.
 59. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle; a second rotaryflywheel connectable with a transmission of the vehicle by a frictionclutch; at least one antifriction bearing between said flywheels; and atleast one damper operative to oppose rotation of said flywheels relativeto each other and disposed in an annular chamber defined at least inpart by said first flywheel, said damper including energy storingelements acting in the circumferential direction of said flywheels andsaid clutch including a cover affixed to said second flywheel andincluding a substantially axially extending portion which at leastpartially surrounds said second flywheel, said cover being provided withstressing portions extending into said chamber and engaging said energystoring elements.
 60. A torque transmitting apparatus for use in motorvehicles, comprising a first rotary flywheel connectable with an engineof a vehicle; a second rotary flywheel connectable with a transmissionof the vehicle by a friction clutch and including a substantiallyradially extending friction surface having a radially outermost portionand a radially innermost portion; at least one antifriction bearingbetween said flywheels; and at least one damper operative to opposerotation of said flywheels relative to each other and disposed in anannular chamber defined at least in part by said first flywheel andbeing at least substantially sealed from the atmosphere, said chamberhaving a radially inner portion extending radially inwardly from theoutermost portion toward the innermost portion of said friction surfaceand terminating at most midway between said innermost and outermostportions, said damper including energy storing elements acting in thecircumferential direction of said flywheels and said clutch including acover affixed to said second flywheel and provided with stressingportions extending into said chamber and engaging said energy storingelements, said friction clutch further including a pressure plate onsaid cover and a clutch plate between said pressure plate and saidfriction surface.
 61. A torque transmitting apparatus for use in motorvehicles, comprising a first rotary flywheel connectable with an engineof a vehicle and including a portion which is immediately adjacent theengine; a second rotary flywheel connectable with a transmission of thevehicle by a friction clutch and having a substantially radiallyextending friction surface adjacent a clutch plate of said clutch, saidsecond flywheel including a portion which is immediately adjacent saidfirst flywheel and defines therewith a narrow clearance extendingradially of said flywheels; at least one antifriction bearing betweensaid flywheels; and at least one damper operative to oppose rotation ofsaid flywheels relative to each other and disposed in an annular chamberdefined at least in part by said first flywheel, said damper includingenergy storing elements acting in the circumferential direction of saidflywheels and said clutch including a cover affixed to said secondflywheel and provided with stressing portions extending into saidchamber and engaging said energy storing elements.
 62. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle; a second rotaryflywheel connectable with a transmission of the vehicle by a frictionclutch, said flywheels having portions which are immediately adjacenteach other and define a narrow clearance and said second flywheelfurther having a friction surface adjacent a clutch plate of saidfriction clutch, said portion of said second flywheel having at leastone opening disposed radially inwardly of said friction surface andcommunicating with said clearance; at least one antifriction bearingbetween said flywheels; and at least one damper operative to opposerotation of said flywheels relative to each other and disposed in anannular chamber defined at least in part by said first flywheel, saiddamper including energy storing elements acting in the circumferentialdirection of said flywheels and said clutch further including a coveraffixed to said second flywheel and provided with stressing portionsextending into said chamber and engaging said energy storing elements.63. A torque transmitting apparatus for use in motor vehicles,comprising a first rotary flywheel including a substantially radiallyextending disc-shaped portion connectable to a rotary output element ofan engine of a vehicle and an axially extending annular portion rigidwith said disc-shaped portion; a second rotary flywheel connectable witha transmission of the vehicle by a friction clutch and having an annularfriction surface adjacent a clutch plate of said clutch; at least oneantifriction bearing between said flywheels; at least one damperoperative to oppose rotation of said flywheels relative to each otherand disposed in an annular chamber defined in part by said firstflywheel, said at least one damper including energy storing elementsacting in the circumferential direction of said flywheels and saidclutch further including a cover affixed to said second flywheel andprovided with stressing portions extending into said chamber andengaging said energy storing elements, said chamber having a radiallyoutermost portion which is surrounded by said annular portion; and anannular wall adjacent said annular portion and bounding a portion ofsaid chamber.
 64. The apparatus of claim 63, wherein said wall surroundssaid cover.
 65. The apparatus of claim 63, further comprising a securingmember provided with said stressing portions and connected with saidcover, said wall surrounding said securing member.
 66. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle; a second rotaryflywheel connectable with a transmission of the vehicle by a frictionclutch, said flywheels having portions which directly define a narrowclearance and said portion of said first flywheel being immediatelyadjacent the engine, said portion of said second flywheel having afriction surface adjacent a clutch plate of said clutch; at least oneantifriction bearing between said flywheels; at least one damperoperative to oppose rotation of said flywheels relative to each otherand disposed in an annular chamber defined at least in part by saidfirst flywheel, said at least one damper including energy storingelements acting in the circumferential direction of said flywheels andsaid clutch further including a cover affixed to said second flywheeland provided with stressing portions extending into said chamber andengaging said energy storing elements; and a seal for said chamber, saidseal being disposed in said clearance.
 67. The apparatus of claim 66,wherein said seal is disposed between said first flywheel and saidcover.
 68. The apparatus of claim 66, wherein said seal is disposedbetween said first flywheel and a securing member connected to saidcover and provided with said stressing portions.
 69. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle; a second rotaryflywheel connectable with a transmission of the vehicle by a frictionclutch, said flywheels defining a passage for a component of thetransmission; at least one antifriction bearing between said flywheels,said passage being surrounded by said at least one bearing and saidfirst flywheel having first holes disposed radially outwardly of saidpassage to receive rotary fasteners which secure the first flywheel to arotary output element of the engine, said first openings being disposedradially outwardly of said at least one bearing and said second flywheelhaving second openings in at least partial alignment with said firstopenings to afford access to said fasteners extending into said firstopenings; and at least one damper operative to oppose rotation of saidflywheels relative to each other and disposed in an annular chamberdefined at least in part by said first flywheel, said at least onedamper including energy storing elements acting in the circumferentialdirection of said flywheels and said clutch including a cover affixed tosaid second flywheel and provided with stressing portions extending intosaid chamber and engaging said energy storing elements.
 70. Theapparatus of claim 69, wherein one of said flywheels includes an annularprotuberance and said at least one bearing surrounds said protuberance.71. The apparatus of claim 70, further comprising a supply of viscousfluid at least partially filling said chamber, said protuberance beingprovided on said first flywheel.
 72. A torque transmitting apparatus foruse in motor vehicles, comprising a first rotary flywheel connectablewith an engine of a vehicle; a second rotary flywheel connectable with atransmission of the vehicle by a friction clutch; said flywheel having afirst side facing away from and a second side facing toward said secondflywheel, said first flywheel further having holes extending betweensaid sides thereof; fasteners having heads adjacent said second side andexternally threaded shanks extending through said holes to secure saidfirst flywheel to a rotary output element of the engine, said secondflywheel having second holes affording access to but preventing passageof the heads of said fasteners therethrough; at least one antifrictionbearing between said flywheels; and at least one damper operative tooppose rotation of said flywheels relative to each other and disposed inan annular chamber defined at least in part by said first flywheel, saiddamper including energy storing elements acting in the circumferentialdirection of said flywheels and said clutch including a cover affixed tosaid second flywheel and provided with stressing portions extending intosaid chamber and engaging said energy storing elements.
 73. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle and havingholes; means for fastening said flywheel to a rotary output element ofthe engine, said fastening means including fasteners having portionsextending into said holes; means for preventing complete withdrawal ofsaid portions of said fasteners from the respective holes; a secondrotary flywheel connectable with a transmission of the vehicle by afriction clutch; at least one antifriction bearing between saidflywheels; and at least one damper operative to oppose rotation of saidflywheels relative to each other and disposed in an annular chamberdefined at least in part y said first flywheel, said at least one damperincluding energy storing elements acting in the circumferentialdirection of said flywheels and said clutch including a cover affixed tosaid second flywheel and provided with stressing portions extending intosaid chamber and engaging said energy storing elements.
 74. Theapparatus of claim 73, wherein said preventing means comprisesdeformable parts.
 75. A torque transmitting apparatus for use in motorvehicles, comprising a first rotary flywheel connectable with an engineof a vehicle and having first holes; means for fastening said firstflywheel to a rotary output element of the engine, said fastening meansincluding fasteners in said holes; a second rotary flywheel connectablewith a transmission of the vehicle by a friction clutch, said flywheelsand said friction clutch together constituting a preassembled unit whichis connectable to the rotary output element of the engine by saidfastening means; at least one antifriction bearing between saidflywheels; and at least one damper operative to oppose rotation of saidflywheels relative to each other and disposed in an annular chamberdefined at least in part by said first flywheel, said damper includingenergy storing elements acting in the circumferential direction of saidflywheels and said clutch including a cover affixed to said secondflywheel and provided with stressing portions extending into saidchamber and engaging said energy storing elements, said clutch furthercomprising a clutch plate and a diaphragm spring having second holes inat least partial alignment with said first holes so as to permitengagement of a tool with the fasteners in said first holes, said clutchplate having third holes each in at least partial alignment with one ofsaid second holes and said clutch plate being disposed between saiddiaphragm spring and said first flywheel.
 76. The apparatus of claim 75,wherein each of said first holes registers with one of said third holes.77. The apparatus of claim 75, wherein said fasteners have headsconfronting said diaphragm spring and the dimensions of said secondholes are such that they prevent the heads of said fasteners frompassing therethrough.
 78. The apparatus of claim 75, wherein saidfasteners have heads confronting said clutch plate and the dimensions ofsaid third holes are such that they prevent the heads of said fastenersfrom passing therethrough.
 79. A torque transmitting apparatus for usein motor vehicles, comprising a first rotary flywheel connectable withan engine of a vehicle; a second rotary flywheel connectable with atransmission of the vehicle by a friction clutch, said first flywheelhaving a first side facing away from said friction clutch, a second sidefacing toward said friction clutch and holes extending between saidfirst and second sides; means for fastening said first flywheel to arotary output element of the engine, said fastening means includingfasteners having heads at said second side and threaded shanks extendinginto said holes, said friction clutch having an internal space and saidheads being receivable in said space in such positions that the shanksof said fasteners do not extend beyond the first side of said firstflywheel; at least one antifriction bearing between said flywheels; andat least one damper operative to oppose rotation of said flywheelsrelative to each other and disposed in an annular chamber defined atleast in part by said first flywheel, said damper including rotaryenergy storing elements acting the circumferential direction of saidflywheels and said clutch including a cover affixed to said secondflywheel and provided with stressing portions extending into saidchamber and engaging said energy storing elements, said flywheels, saidat least one bearing, said at least one damper and said friction clutchtogether constituting a preassembled unit which is connectable to theoutput element of the engine by said fasteners and said preassembledunit further comprising means for preventing complete withdrawal of saidshanks of said fasteners from the respective holes.
 80. A torquetransmitting apparatus for use in motor vehicles, comprising a firstrotary flywheel connectable with an engine of a vehicle; a second rotaryflywheel connectable with a transmission of the vehicle by a frictionclutch; at least one antifriction bearing between said flywheels; and atleast one damper operative to oppose rotation of said flywheels relativeto each other and disposed in an annular chamber defined at least inpart by said first flywheel, said at least one damper including energystoring elements acting in the circumferential direction of saidflywheels and said clutch including a cover affixed to said secondflywheel and provided with stressing portions extending into saidchamber and engaging said energy storing elements, said cover includingan axially extending radially outer portion and said chamber surroundingsaid axially extending portion.
 81. A torque transmitting apparatus foruse in motor vehicles, comprising a first rotary flywheel connectablewith an engine of a vehicle; a second rotary flywheel connectable with atransmission of the vehicle by a friction clutch; at least oneantifriction bearing between said flywheels; and at least one damperoperative to oppose rotation of said flywheels relative to each otherand disposed in an annular chamber defined at least in part by saidfirst flywheel, said at least one damper including energy storingelements acting in the circumferential direction of said flywheels andsaid clutch including a cover affixed to said second flywheel andprovided with stressing portions extending into said chamber andengaging said energy storing elements, said cover including an axiallyextending radially outer portion and said stressing portions beingprovided on said axially extending portion, said stressing portionsbeing disposed substantially radially of said axially extending portion.82. A torque transmitting apparatus for use in motor vehicles,comprising a first rotary flywheel connectable with an engine of avehicle; a second rotary flywheel connectable with a transmission of thevehicle by a friction clutch; at least one antifriction bearing betweensaid flywheels; and at least one damper operative to oppose rotation ofsaid flywheels relative to each other and disposed in an annular chamberdefined at least in part by said first flywheel, said at least onedamper including energy storing elements acting in the circumferentialdirection of said flywheels and said clutch including a cover affixed tosaid second flywheel and provided with stressing portions extending intosaid chamber and engaging said energy storing elements, said coverincluding an axially extending radially outer portion and said energystoring elements being radially outwardly adjacent said axiallyextending portion.
 83. A torque transmitting apparatus for use in motorvehicles, comprising a first rotary flywheel connectable with an engineof a vehicle; a second rotary flywheel connectable with a transmissionof the vehicle by a friction clutch; at least one antifriction bearingbetween said flywheels; at least one damper operative to oppose rotationof said flywheels relative to each other and disposed in an annularchamber defined at least in part by said first flywheel, said damperincluding energy storing elements acting in the circumferentialdirection of said flywheels and said clutch including a cover affixed tosaid second flywheel and provided with stressing portions extending intosaid chamber and engaging said energy storing elements; and a thermalinsulator between said cover and said second flywheel.